Exposure apparatus, exposure method, and method for producing device

ABSTRACT

An exposure apparatus irradiates a substrate with light via a projection system and liquid, and includes a stage that moves below the projection system, and a light-receiving element having a light-receiving surface. An optical member provided on the stage has a first surface contacting the liquid when moved to face the projection system, and a second surface contacting a gas and transmitting light having come from the projection system via the liquid and the first surface. The optical member is configured such that at least a large-angle ray of the light, which has an angle with an optical axis of the projection system sufficiently large to undergo total reflection at an end surface of the projection system when the liquid is absent, travels from the projection system to the second surface without passing through gas. The second surface transmits the large-angle ray, which is received by the light-receiving surface.

CROSS-REFERENCE

This is a Divisional of U.S. patent application Ser. No. 13/633,599filed Oct. 2, 2012, which in turn is a Divisional of U.S. patentapplication Ser. No. 11/390,178 filed Mar. 28, 2006 (now U.S. Pat. No.8,305,552), which is a Continuation of International Application No.PCT/JP2004/014693 which was filed on Sep. 29, 2004 claiming theconventional priority of Japanese patent Application No. 2003-338420filed on Sep. 29, 2003, No. 2003-344938 filed on Oct. 2, 2003, and No.2004-042931 filed on Feb. 19, 2004. The disclosures of these priorapplications are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exposure apparatus and an exposuremethod in which a pattern formed on a mask is transferred onto asubstrate to expose the substrate therewith, and a method for producinga device based on the use of the exposure apparatus.

2. Description of the Related Art

The photolithography step is provided usually as one of the steps ofproducing the microdevice including, for example, semiconductorelements, liquid crystal display elements, image pickup devices (forexample, CCD (Charge Coupled Device)), and thin film magnetic heads. Inthe photolithography step, the exposure apparatus is used, in which areduced image of a pattern formed on a mask or a reticle (hereinaftergenerally referred to as “mask”, if necessary) is subjected to theprojection exposure on a substrate as an exposure objective(semiconductor wafer or glass plate coated with photoresist). In recentyears, the reduction projection exposure apparatus (so-called stepper)which is based on the step-and-repeat system or the exposure apparatuswhich is based on the step-and-scan system is used in many cases.

The stepper is such an exposure apparatus that the substrate is placedon a substrate stage which is movable two-dimensionally, and thesubstrate is moved in a stepwise manner (subjected to the stepping) bythe substrate stage to successively repeat the operation in which eachof shot areas on the substrate is subjected to the full field exposurewith the reduced image of the pattern of the mask. The exposureapparatus based on the step-and-scan system is such an exposureapparatus that a mask stage on which the mask is placed and a substratestage on which the substrate is placed are moved mutually synchronouslywith respect to a projection optical system in a state in which the maskis radiated with a slit-shaped pulse exposure beam, while a part of apattern formed on the mask is successively transferred onto a shot areaof the substrate, and the substrate is subjected to the stepping uponthe completion of the transfer of the pattern to one shot area toperform the transfer of the pattern to another shot area.

The exposure apparatus as described above has a plurality of opticalsensors (light receivers) for receiving the exposure beam through theprojection optical system. Various types of mechanical adjustments andoptical adjustments are performed and various types of operationconditions are determined on the basis of the outputs of the opticalsensors to optimize the exposure operation to be performed when thesubstrate is actually exposed. Those provided on the substrate stageinclude, for example, an uneven illuminance sensor (irradiationirregularity sensor) for measuring the uneven illuminance (light amountdistribution) of the exposure beam which has passed through theprojection optical system and/or measuring the totalized uneven lightamount, and a radiation amount sensor (dose sensor) for measuring theradiation amount (light amount) of the exposure beam which has passedthrough the projection optical system. The irradiation irregularitysensor as described above is disclosed, for example, in Japanese PatentApplication Laid-open No. 08-316133. The dose sensor as described aboveis disclosed, for example, in International Publication No. 01/008205.

In recent years, it is demanded to realize the higher resolution of theprojection optical system in order to respond to the further advance ofthe higher integration of the device pattern. The shorter the exposurewavelength to be used is, the higher the resolution of the projectionoptical system is. The larger the numerical aperture of the projectionoptical system is, the higher the resolution of the projection opticalsystem is. Therefore, the exposure wavelength, which is used for theexposure apparatus, is shortened year by year, and the numericalaperture of the projection optical system is increased as well. Theexposure wavelength, which is dominantly used at present, is 248 nm ofthe KrF excimer laser. However, the exposure wavelength of 193 nm of theArF excimer laser, which is shorter than the above, is also practicallyused in some situations. When the exposure is performed, the depth offocus (DOF) is also important in the same manner as the resolution. Theresolution R and the depth of focus δ are represented by the followingexpressions respectively.

R=k ₁·λ/NA  (1)

δ=±k ₂·λ/NA²  (2)

In the expressions, λ represents the exposure wavelength, NA representsthe numerical aperture of the projection optical system, and k₁ and k₂represent the process coefficients. According to the expressions (1) and(2), the following fact is appreciated. That is, when the exposurewavelength λ is shortened and the numerical aperture NA is increased inorder to enhance the resolution R, then the depth of focus δ isnarrowed.

If the depth of focus δ is too narrowed, it is difficult to match thesubstrate surface with respect to the image plane of the projectionoptical system. It is feared that the margin is insufficient during theexposure operation. Accordingly, the liquid immersion method has beensuggested, which is disclosed, for example, in International PublicationNo. 99/49504 as a method for substantially shortening the exposurewavelength and widening the depth of focus. In this liquid immersionmethod, the space between the lower surface of the projection opticalsystem and the substrate surface is filled with a liquid such as wateror any organic solvent to form a liquid immersion area so that theresolution is improved and the depth of focus is magnified about n timesby utilizing the fact that the wavelength of the exposure beam in theliquid is 1/n as compared with that in the air (n represents therefractive index of the liquid, which is about 1.2 to 1.6 in ordinarycases).

The optical sensor (light receiver) described above has thelight-transmitting section which is arranged on the image plane side ofthe projection optical system, wherein the light is received through thelight-transmitting section. Therefore, when the numerical aperture ofthe projection optical system is increased as a result of the adoptionof the liquid immersion method or the like, and the incident angle ofthe exposure beam (angle formed by the outermost ray and the opticalaxis) is increased, then the expansion of the light outgone from thelight-transmitting section is increased as well, and it is feared thatthe light cannot be received satisfactorily.

SUMMARY OF THE INVENTION

The present invention has been made taking the foregoing circumstancesinto consideration, an object of which is to provide an exposureapparatus and an exposure method in which various measuring operationscan be performed accurately and various measuring operations can beperformed satisfactorily especially when the exposure method based onthe liquid immersion system is adopted, and a method for producing adevice based on the use of the exposure apparatus.

Another object of the present invention is to provide an exposureapparatus and an exposure method in which a light receiver capable ofsatisfactorily receiving a light beam which has passed through aprojection optical system is provided, and a method for producing adevice.

In order to achieve the objects as described above, the presentinvention adopts the following constructions.

According to a first aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam through a liquid onto the substrate; the exposureapparatus comprising a projection optical system; and a measuring unitwhich has a light-transmitting section provided on an image plane sideof the projection optical system and a light receiver for receiving,through the light-transmitting section, the exposure beam which haspassed through the projection optical system; wherein the light receiverof the measuring unit receives the exposure beam which has passedthrough the light-transmitting section and the projection optical systemin a state in which no liquid exists between the projection opticalsystem and the light-transmitting section. The measuring unit may be anirradiation irregularity sensor (uneven illuminance sensor), a dosesensor (radiation amount sensor), or a spatial image-measuring unit.

According to this invention, the exposure beam, which has passed throughthe projection optical system, is received by the light receiver(optical receiver or light-receiving module or unit) of the measuringunit via the light-transmitting section arranged on the image plane sideof the projection optical system in the state in which the liquid is notsupplied to the image plane side of the projection optical system.

According to a second aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam onto the substrate; the exposure apparatus comprising aprojection optical system; and a measuring unit which is arranged on animage plane side of the projection optical system and which has alight-transmitting section for allowing the exposure beam from theprojection optical system to come thereinto, a light receiver, and alight-collecting member for allowing the light beam from thelight-transmitting section to come into the light receiver; wherein thelight-collecting member is arranged between the light-transmittingsection and the light receiver so that the exposure beam from theprojection optical system comes into the light-collecting member withoutpassing through any gas.

According to this invention, the light beam, which is included in theexposure beam come from the projection optical system and which has beentransmitted through the light-transmitting section, is allowed to comeinto the light-collecting member and collected without passing throughthe gas. Various methods are available in order to introduce the lightbeam from the light-transmitting section into the light-collectingmember without passing through the gas. However, the light-transmittingsection and the light-collecting member may be joined to one another.Alternatively, a light-transmissive medium other than the gas, whichincludes, for example, liquid, supercritical fluid, paste, and solid,may be intervened, for example, in a form of thin film between thelight-transmitting section and the light-collecting member.

According to a third aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam through a liquid onto the substrate; the exposureapparatus comprising a projection optical system; and a measuring unitwhich has a plate-shaped member provided with one surface arranged to beopposed to the projection optical system and provided with alight-transmitting section formed at a part of another surface and whichhas a light receiver for receiving the light beam from thelight-transmitting section; wherein the light receiver of the measuringunit receives the exposure beam through the liquid provided between theprojection optical system and the plate-shaped member.

According to this invention, the exposure beam from the projectionoptical system comes into the plate-shaped member through the liquid,and the light beam, which is included in the light beam come into theplate-shaped member and which is transmitted through thelight-transmitting section, is received by the light receiver providedfor the measuring unit. Therefore, the exposure beam can be measured inthe state of the liquid immersion exposure.

According to a fourth aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam through a liquid onto the substrate; the exposureapparatus comprising a projection optical system; and a measuring unitwhich has a light-transmitting section provided on an image plane sideof the projection optical system for allowing the exposure beam from theprojection optical system to come thereinto via the liquid, a lightreceiver, and an optical system for allowing the light beam from thelight-transmitting section to come into the light receiver; wherein theoptical system is arranged between the light-transmitting section andthe light receiver so that the light beam from the light-transmittingsection comes into the optical system without passing through any gas.

According to this invention, the light beam, which is included in theexposure beam come from the projection optical system and which haspassed through the light-transmitting section, is introduced into theoptical system provided for the measuring unit so that the light beamdoes not pass through the gas, and the light beam comes into the lightreceiver. Therefore, the light receiver can efficiently receive thelight beam transmitted through the light-transmitting section. In orderto introduce the light beam from the light-transmitting section into theoptical system so that the light beam does not pass through the gas, amedium other than the gas may be intervened as described above. Theoptical system may be one optical member. Alternatively, the opticalsystem may be composed of a plurality of optical members.

According to a fifth aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam through a liquid onto the substrate; the exposureapparatus comprising a projection optical system; an optical memberwhich has a light-transmitting section arranged on an image plane sideof the projection optical system; and a light receiver which receivesthe light beam which has passed through the projection optical systemvia the optical member; wherein a space between the light receiver andthe optical member is filled with the liquid.

The following operation is assumed in the liquid immersion exposure.That is, when the light beam, which has passed through the projectionoptical system via the optical member arranged on the image plane sideof the projection optical system, is received by the light receiver, thelight beam is radiated onto the light receiver to perform thelight-receiving operation in the state in which the space between theprojection optical system and the optical member is filled with theliquid. According to the present invention, the space between theoptical member and the light receiver is also filled with the liquid.Accordingly, the light beam, which has passed through the projectionoptical system, can be satisfactorily received by the light receiver. Inother words, when the space between the projection optical system andthe optical member is filled with the liquid, it is possible to increasethe numerical aperture NA of the projection optical system. However, itis necessary that the numerical aperture NA of the optical system of thelight receiver is also changed depending on the numerical aperture NA ofthe projection optical system. That is, if the numerical aperture NA ofthe light receiver is not improved depending on the numerical apertureNA of the projection optical system, then a situation arises such thatthe light beam, which has passed through the projection optical system,cannot be incorporated satisfactorily by the light receiver, and thelight beam cannot be received in a well-suited manner. Therefore, whenthe numerical aperture NA of the projection optical system is improvedby filling the space between the projection optical system and theoptical member with the liquid, then the space between the opticalmember and the light receiver is also filled with the liquid to improvethe numerical aperture NA of the optical system of the light receiver,and thus the light beam, which has passed through the projection opticalsystem, can be satisfactorily received by the light receiver. Theoptical member referred to herein includes all members having thelight-transmitting section.

According to a sixth aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by irradiating anexposure beam onto the substrate; the exposure apparatus comprising aprojection optical system; an optical member which has alight-transmitting section arranged on an image plane side of theprojection optical system; and a light receiver which receives the lightbeam which has passed through the projection optical system via theoptical member; wherein a space between the light receiver and theoptical member is filled with a liquid.

According to the present invention, the numerical aperture NA of theoptical system of the light receiver can be improved by filling thespace between the optical member and the light receiver with the liquid.Thus, it is possible to perform the light-receiving operationsatisfactorily. The arrangement of the present invention, in which thespace between the optical member and the light receiver is filled withthe liquid, is also applicable to a dry exposure apparatus whichperforms the exposure without passing through the liquid, in addition tothe application to the liquid immersion exposure apparatus.

According to a seventh aspect of the present invention, there isprovided an exposure apparatus which exposes a substrate by irradiatingan exposure beam onto the substrate through a liquid; the exposureapparatus comprising a projection optical system; an optical memberwhich has a light-transmitting section arranged on an image plane sideof the projection optical system; and a light receiver having alight-receiving element which receives the light beam which has passedthrough the projection optical system via the optical member and whichis provided in contact with the optical member.

According to the present invention, the light-receiving element of thelight receiver is arranged to make contact with the optical member.Accordingly, even when the space between the projection optical systemand the optical member is filled with the liquid to substantiallyimprove the numerical aperture NA of the projection optical system, thelight receiver can satisfactorily receive the light beam which haspassed through the projection optical system.

According to an eighth aspect of the present invention, there isprovided an exposure apparatus which exposes a substrate by irradiatingan exposure beam onto the substrate through a liquid; the exposureapparatus comprising a projection optical system; an optical memberwhich has a light-transmitting section arranged on an image plane sideof the projection optical system and which has a through-hole formed ata predetermined position; and a light receiver which receives the lightbeam which has passed through the projection optical system via theoptical member.

According to the present invention, the through-hole is provided for theoptical member, and thus the liquid, which is disposed between theprojection optical system and the optical member, can move (escape)through the through-hole. Therefore, no difference appears between thepressure of the liquid disposed between the projection optical systemand the optical member and the pressure of the liquid disposed betweenthe optical member and the light receiver. No inconvenience arises,which would be otherwise caused, for example, such that the opticalmember is warped. Any great pressure fluctuation arises for the liquidbetween the projection optical system and the optical member as well,because the liquid is movable through the through-hole. Therefore, it ispossible to avoid the occurrence of the inconvenience which would beotherwise caused such that the projection optical system is fluctuated(vibrated) due to the pressure fluctuation of the liquid.

According to the present invention, there is provided a method forproducing a device, comprising using the exposure apparatus as definedin any one of the first to eighth aspects. According to the presentinvention, the light receiver can satisfactorily receive the light beamwhich has passed through the projection optical system. Therefore, theexposure process can be performed accurately in a state in which theoptimum exposure condition is established on the basis of thelight-receiving result. It is possible to produce the device havingdesired performance.

According to a ninth aspect of the present invention, there is providedan exposure method for exposing a substrate by irradiating an exposurebeam via a projection optical system and a liquid onto the substrate;the exposure method comprising a step of installing a measuring unit formeasuring the exposure beam on a side of a light-outgoing end of theprojection optical system; a step of measuring the exposure beam byusing the measuring unit without allowing the liquid to intervene in anoptical path space on the side of the light-outgoing end of theprojection optical system; and a step of exposing the substrate whileallowing the liquid to intervene in the optical path space on the basisof a measurement result; wherein an incident angle of the exposure beamcome from the projection optical system into an interface between theoptical path space and the light-outgoing end of the projection opticalsystem differs between the measuring step and the exposure step.According to this method, the incident angle of the exposure beam comeinto the interface between the optical path space and the light-outgoingend of the projection optical system in the measuring step is adjustedto be smaller than the incident angle in the exposure step. Accordingly,even when the liquid is absent in the optical path space between theprojection optical system and the measuring unit, the measuring unit cansatisfactorily receive the exposure beam. The received light beam can beused to execute the adjustment of the imaging state and the exposurebeam.

According to a tenth aspect of the present invention, there is providedan exposure method for exposing a substrate by irradiating an exposurebeam via a projection optical system onto the substrate; the exposuremethod comprising receiving the exposure beam outgone from theprojection optical system by a light receiver; and exposing thesubstrate by irradiating the exposure beam via the projection opticalsystem and a liquid. According to this method, the exposure beam can befed to the light-receiving element without passing through any gas.Therefore, even when the numerical aperture of the projection opticalsystem is increased, it is possible to satisfactorily receive theexposure beam which has passed through the projection optical system.

According to an eleventh aspect of the present invention, there isprovided an exposure method for exposing a substrate by irradiating anexposure beam through a projection optical system onto the substrate;the exposure method comprising receiving the light beam which has passedthrough the projection optical system by a light receiver via an opticalmember having a light-transmitting section arranged on an image planeside of the projection optical system; and exposing the substrate byirradiating the exposure beam onto the substrate via the projectionoptical system; wherein a space between the light receiver and theoptical member is filled with a liquid. According to this method, thespace between the light receiver and the optical member is filled withthe liquid. Therefore, even when the numerical aperture of theprojection optical system is increased, it is possible to satisfactorilyreceive the exposure beam come from the light-transmitting section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic arrangement of an exposure apparatus accordingto a first embodiment of the present invention.

FIG. 2 shows a front view illustrating an example of an aperturediaphragm plate 8.

FIGS. 3A and 3B show an exemplary arrangement of an exposure beam sensor27.

FIG. 4 shows a flow chart illustrating an exemplary operation to beperformed upon the start of the exposure process effected by theexposure apparatus according to the first embodiment of the presentinvention.

FIGS. 5A and 5B show a schematic arrangement of an irradiationirregularity sensor provided for an exposure apparatus according to asecond embodiment of the present invention.

FIGS. 6A and 6B show a modified embodiment of the irradiationirregularity sensor provided for the exposure apparatus according to thesecond embodiment of the present invention.

FIGS. 7A and 7B show a schematic arrangement of an irradiationirregularity sensor provided for an exposure apparatus according to athird embodiment of the present invention.

FIG. 8 shows a perspective view illustrating another example of aplano-convex lens provided for the irradiation irregularity sensorprovided for the exposure apparatus according to the third embodiment ofthe present invention.

FIG. 9 shows a sectional view illustrating a schematic arrangement of anirradiation irregularity sensor provided for an exposure apparatusaccording to a fourth embodiment of the present invention.

FIG. 10 shows a sectional view illustrating a schematic arrangement ofan irradiation irregularity sensor provided for an exposure apparatusaccording to a fifth embodiment of the present invention.

FIGS. 11A and 113 show a schematic arrangement of a dose sensor providedfor an exposure apparatus according to a sixth embodiment of the presentinvention.

FIG. 12 shows a perspective view illustrating an exemplary structure ofa light-collecting plate formed with apertures for an microlens array.

FIG. 13 shows a schematic arrangement of a dose sensor provided for anexposure apparatus according to a seventh embodiment of the presentinvention.

FIG. 14 shows a schematic arrangement of a dose sensor provided for anexposure apparatus according to an eighth embodiment of the presentinvention.

FIGS. 15A and 153 show a schematic arrangement of an irradiationirregularity sensor provided for an exposure apparatus according to aninth embodiment of the present invention.

FIG. 16 shows a schematic arrangement of an irradiation irregularitysensor provided for an exposure apparatus according to a tenthembodiment of the present invention.

FIG. 17 shows a modified embodiment of the irradiation irregularitysensor 40 provided for the exposure apparatus according to the secondembodiment.

FIG. 18 shows a flow chart illustrating exemplary steps of producing amicrodevice.

FIG. 19 shows a detailed exemplary flow of Step S23 shown in FIG. 11adopted in the case of a semiconductor device.

FIG. 20 shows a schematic arrangement illustrating an embodiment of anexposure apparatus according to the present invention.

FIG. 21 shows a schematic arrangement illustrating those disposed in thevicinity of an end portion of a projection optical system, a liquidsupply mechanism, and a liquid recovery mechanism.

FIG. 22 shows a plan view illustrating a positional relationship amongthe projection area of the projection optical system, the liquid supplymechanism, and the liquid recovery mechanism.

FIG. 23 shows a schematic arrangement illustrating an embodiment of alight receiver according to the present invention.

FIG. 24 schematically shows a state in which the light receiver performsthe measuring operation.

FIG. 25 shows a magnified view illustrating major parts to depict anembodiment of an optical member and a light receiver according to thepresent invention.

FIG. 26 shows a plan view illustrating the optical member shown in FIG.25.

FIGS. 27A and 27B show an exemplary light-transmitting section of theoptical member.

FIG. 28 shows an exemplary light-receiving signal received by the lightreceiver.

FIG. 29 shows an exemplary mask to be used when the imagingcharacteristic of the projection optical system is measured.

FIG. 30 shows an exemplary mask to be used when the imagingcharacteristic of the projection optical system is measured.

FIG. 31 shows an exemplary mask to be used when the imagingcharacteristic of the projection optical system is measured.

FIG. 32 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 33 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 34 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 35 shows a plan view illustrating the optical member shown in FIG.34.

FIGS. 36A to 36C show an exemplary procedure for forming the liquidimmersion area.

FIG. 37 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 38 shows a plan view illustrating the optical member shown in FIG.37.

FIG. 39 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 40 shows a plan view illustrating the optical member shown in FIG.39.

FIG. 41 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 42 shows a plan view illustrating a state in which a plurality oflight receivers are arranged on a substrate stage.

FIG. 43 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 44 shows a magnified view illustrating major parts to depictanother embodiment of an optical member and a light receiver accordingto the present invention.

FIG. 45 illustrates the condition under which the total reflection isnot caused for a part of the ray of the exposure beam at the end portionof the projection optical system in relation to the refractive index ofthe medium to make contact with the end portion of the projectionoptical system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

An explanation will be made in detail below about the exposure apparatusand the method for producing the device according to embodiments of thepresent invention with reference to the drawings. However, the presentinvention is not limited thereto.

First Embodiment

FIG. 1 shows a schematic arrangement of an exposure apparatus accordingto a first embodiment of the present invention. The exposure apparatusEX shown in FIG. 1 is an exposure apparatus based on the liquidimmersion system in which the exposure is performed through a liquid(pure water) LQ disposed between a projection optical system PL and awafer W. The exposure apparatus uses a reticle R formed with a circuitpattern DP of a semiconductor element to transfer an image of thecircuit pattern DP to the wafer W in the step-and-repeat manner.

In the following description, the XYZ rectangular coordinate systemshown in the drawing is established. An explanation will be made aboutthe positional relationship in relation to the respective members withreference to the XYZ rectangular coordinate system. The XYZ rectangularcoordinate system is established so that the X axis and the Y axis areparallel to the wafer W, and the Z axis is established in the directionperpendicular to the wafer W. The XYZ rectangular coordinate system inthe drawing is actually established such that the XY plane resides inthe plane parallel to the horizontal plane, and the Z axis isestablished in the vertically upward direction.

The exposure apparatus EX shown in FIG. 1 is provided with an ArFexcimer laser light source for supplying the light beam having awavelength of 193 nm (ArF), as the light source 1 for supplying theexposure beam. The substantially parallel light flux, which is radiatedfrom the light source 1, is shaped into a light flux having apredetermined cross section by the aid of a beam-shaping optical system2, and then the light flux comes into an interference-reducing section3. The interference-reducing section 3 functions to reduce theoccurrence of the interference pattern on the reticle R as a radiationobjective surface (as well as on the wafer W).

Details of the interference-reducing section 3 are disclosed, forexample, in Japanese Patent Application Laid-open No. 59-226317. Thelight flux from the interference-reducing section 3 passes through afirst fly's eye lens (first optical integrator) 4 to form a large numberof light sources on the back focal plane thereof. The light beams, whichcome from the large number of light sources, are deflected by avibration mirror 5. After that, the light beams illuminate, in asuperimposed manner, a second fly's eye lens (second optical integrator)7 via a relay optical system 6. Accordingly, a secondary light source,which is composed of a large number of light sources, is formed at theback focal plane of the second fly's eye lens 7.

An aperture diaphragm plate 8, which is rotatable by a driving motor 8f, is arranged at an outgoing plane CJ of the second fly's eye lens 7,i.e., at the pupil plane of the illumination optical system(illumination system) IS (plane optically conjugate with the pupil planeof the projection optical system PL). FIG. 2 shows a front viewillustrating an example of the aperture diaphragm plate 8. As shown inFIG. 2, the aperture diaphragm plate 8 is composed of a disk which isconstructed rotatably about a rotary shaft O. Those formed along thecircumferential direction are a circular aperture diaphragm 8 a for theordinary illumination, an aperture diaphragm 8 b for the zonalillumination, an aperture diaphragm 8 c for the four-spot modifiedillumination (four-spot illumination), a small circular aperturediaphragm 8 d for the small coherence factor (small σ), and a variableaperture diaphragm 8 e to be used for measuring, for example, the unevenilluminance or the radiation amount of the exposure beam. Large circlesdepicted by broken lines in FIG. 2 represent the size of the circularaperture diaphragm 8 a for the ordinary illumination, which areillustrated in the drawing in order to compare the size with those ofthe aperture diaphragms 8 b to 8 e.

The coherence factor (σ of the illumination system) is the ratio betweenthe numerical aperture NAr of the projection optical system PL on theside of the reticle R and the numerical aperture NAi of the illuminationoptical system IS, which is defined as follows.

σ=NAi/NAr

The numerical aperture NA of the projection optical system PL usuallyexhibits the numerical aperture NAw on the side of the wafer W. Thenumerical aperture NAr on the side of the reticle is determined asNAr=NAw/M in accordance with the magnification M of the projectionoptical system PL.

The aperture diaphragm 8 e is formed such that the size of the apertureis variable. The σ value can be varied, for example, within a range of0.05 to 0.50. The aperture diaphragm 8 e is provided in order that theangular aperture or the open angle (angle formed by the outermost ray orbeam and the optical axis) of the exposure beam directed toward theimage plane side of the projection optical system PL is adjusted(decreased) when the uneven illuminance and/or the light amount ismeasured without providing the liquid LQ on the image plane side of theprojection optical system PL. In other words, if the liquid LQ is absenton the image plane side of the projection optical system PL, forexample, the exposure beam having a large angular aperture, which is tobe used for the ordinary illumination, involves a part of the light beamwhich undergoes the total reflection at the end portion on the imageplane side of the projection optical system PL and which cannot passthrough the projection optical system PL, because the exposure apparatusof the embodiment of the present invention is the exposure apparatusbased on the liquid immersion system in which the exposure process isperformed through the liquid LQ disposed between the projection opticalsystem PL and the wafer W. The aperture diaphragm 8 e is provided inorder that the angular aperture of the exposure beam directed toward theimage plane side of the projection optical system PL is adjusted toavoid the total reflection by the projection optical system PL. FIG. 2shows the arrangement in which the aperture diaphragm 8 e is providedfor the aperture diaphragm plate 8 separately from the aperturediaphragm 8 d in order to clarify the feature of the present invention.However, the coherence factor of the aperture diaphragm 8 d is also setto about 0.25 to 0.35. Therefore, another arrangement is also available,in which the aperture diaphragm 8 d is used for the measurement, and theaperture diaphragm 8 e is omitted. In this arrangement, the aperture ofthe aperture diaphragm 8 d may be variable.

With reference to FIG. 1 again, the rotary shaft O of the aperturediaphragm plate 8 is connected to a rotary shaft of the driving motor 8f. When the driving motor 8 f is driven to rotate the aperture diaphragmplate 8 about the rotary shaft O, it is possible to switch the aperturediaphragm to be arranged at the outgoing plane CJ of the second fly'seye lens 7. The intensity distribution (light flux distribution) of theexposure beam is changed at the outgoing plane CJ of the second fly'seye lens 7 depending on the aperture diaphragm arranged at the outgoingplane CJ of the second fly's eye lens 7. The driving of the drivingmotor 8 f is controlled by a main control system 20 which integrallycontrols the operation of the entire exposure apparatus EX.

The exposure beam, which is included in the light flux supplied from thesecondary light source formed by the second fly's eye lens 7 and whichhas passed through any one of the aperture diaphragms 8 a to 8 d formedfor the aperture diaphragm plate 8, passes along a condenser opticalsystem 10 and a bending mirror 11, and the exposure beam uniformlyilluminates, in a superimposed manner, the reticle R having thepredetermined circuit pattern DP formed on the lower surface.Accordingly, the image of the pattern of the reticle R in theillumination area is projected at a predetermined projectionmagnification β (β is, for example, ¼ or ⅕) onto the exposure area(projection area) of the wafer W as the substrate arranged on the imageplane of the projection optical system PL via the projection opticalsystem PL which is telecentric on the both sides. The wafer W is adisk-shaped substrate composed of, for example, a semiconductor (siliconor the like) or SOI (silicon on insulator). The components, which rangefrom the beam-shaping optical system 2 to the bending mirror 11 asexplained above, constitute the illumination optical system(illumination system) IS.

The projection optical system PL comprises a plurality of opticalelements such as lenses. In this embodiment, the light beam of the ArFexcimer laser light source in the vacuum ultraviolet region is used asthe exposure beam. Therefore, for example, synthetic quartz or fluorite(calcium fluoride: CaF₂) is used as the material for the optical elementfor constructing the projection optical system PL. Parts of the opticalelements provided for the projection optical system PL are constructedto be movable in the direction of the optical axis AX of the projectionoptical system PL (in the Z direction) and tiltable about the axisparallel to the X axis or about the axis parallel to the Y axis. Theoptical elements are controlled by a lens controller section 14 asdescribed later on. The projection optical system PL is a projectionoptical system which is based on the liquid immersion system forallowing the incoming light flux to form the image on the image planeside in the state in which the liquid LQ is supplied to the image planeside. The numerical aperture (N.A.) is set to be not less than 1 (forexample, 1.00 to 1.40). The projection optical system PL of thisembodiment is based on the dioptric system. However, it goes withoutsaying that the cata-dioptric system and the catoptric system are alsousable.

The reticle R is placed on a reticle stage 13 by the aid of a reticleholder (not shown). The reticle stage 13 is driven by a reticle stagecontrol unit (not shown) on the basis of an instruction from the maincontrol system 20. In this arrangement, the movement of the reticlestage 13 is measured by a reticle interferometer (not shown) and amovement mirror (not shown) provided for the reticle stage 13. Theresult of the measurement is outputted to the main control system 20.

The projection optical system PL is provided with the lens controllersection 14 which measures the temperature and the atmospheric pressureand which controls the optical characteristics such as the imagingcharacteristics of the projection optical system PL to be constantdepending on the change of the environment including, for example, thetemperature and the atmospheric pressure. The lens controller section 14outputs the measured temperature and the atmospheric pressure to themain control system 20. The main control system 20 controls the opticalcharacteristics of, for example, the image-forming optical system of theprojection optical system PL by the aid of the lens controller section14 on the basis of the temperature and the atmospheric pressureoutputted from the lens controller section 14 and the measurement resultobtained by an exposure beam sensor 27 as described later on.

The wafer W is vacuum-chucked by a wafer holder 16 which is contained ina wafer stage 15. The height position of the wafer holder 16 isestablished so that the upper surface of the wafer W is coincident withthe upper surface of the wafer stage 15 when the wafer W is retained onthe wafer holder 16. The wafer stage 15 is constructed such that a pairof X stage and Y stage, which are movable in the X axis direction andthe Y axis direction respectively in the drawing, are overlapped. Theposition in the XY plane is adjustable.

Although not shown in the drawing, the wafer stage 15 includes, forexample, a Z stage which moves the wafer W in the Z axis direction, astage which finely rotates the wafer W in the XY plane, and a stagewhich adjusts the inclination of the wafer W with respect to the XYplane by changing the angle with respect to the Z axis. As describedabove, the wafer stage 15 has the function to effect the movement in theX axis direction, the function to effect the movement in the Y axisdirection, the function to effect the movement in the Z axis direction,the function to effect the rotation about the Z axis, the function toeffect the tilting about the X axis, and the function to effect thetilting about the Y axis.

A movement mirror 17 is attached to one end of the upper surface of thewafer stage 15. A laser interferometer 18 is arranged at a positionopposed to the mirror surface of the movement mirror 17. Although theillustration is simplified in FIG. 1, the movement mirror 17 includes amovement mirror which has a reflecting surface perpendicular to the Xaxis and a movement mirror which has a reflecting surface perpendicularto the Y axis. The laser interferometer 18 includes two laserinterferometers for the X axis for irradiating the laser beam onto themovement mirror 17 along the X axis and a laser interferometer for the Yaxis for irradiating the laser beam onto the movement mirror 17 alongthe Y axis. The X coordinate and the Y coordinate of the wafer stage 15are measured by the one laser interferometer for the X axis and the onelaser interferometer for the Y axis.

The angle of rotation of the wafer stage 15 in the XY plane is measuredin accordance with the difference between the measured values obtainedby the two laser interferometers for the X axis. The information aboutthe X coordinate, the Y coordinate, and the angle of rotation measuredby the laser interferometer 18 is supplied as the stage positioninformation to the main control system 20. The main control system 20outputs a control signal to a stage-driving system 19 while monitoringthe supplied stage position information to control the positioningoperation of the wafer stage 15 in an order of nanometer. A reflectingsurface may be provided on the side surface of the wafer stage 15 inplace of the movement mirror 17. In this arrangement, the substantiallyentire upper surface of the wafer stage 15 can be substantially flush.

The exposure apparatus EX shown in FIG. 1 comprises a liquid supply unit21 and a liquid recovery unit 22 for supplying the liquid LQ to theimage plane side of the projection optical system PL and recovering thesupplied liquid LQ. The liquid supply unit 21 includes, for example, atank for accommodating the liquid LQ and a pressurizing pump. One end ofa supply tube 23 is connected to the liquid supply unit 21. Supplynozzles 24 are connected to the other end of the supply tube 23. Theliquid LQ is supplied via the supply tube 23 and the supply nozzles 24.In this embodiment, the ArF laser beam is used as the exposure beam.Therefore, pure water is used as the liquid LQ. It is not necessarilyindispensable that the exposure apparatus EX is provided, for example,with the tank and the pressurizing pump of the liquid supply unit 21. Atleast a part of the component can be replaced with the equipment of thefactory or the like in which the exposure apparatus EX is installed.

The liquid recovery unit 22 includes, for example, a suction pump and atank for accommodating the recovered liquid LQ. One end of a recoverytube 25 is connected to the liquid recovery unit 22. Recovery nozzles 26are connected to the other end of the recovery tube 25. The liquid LQ,which is supplied to the image plane side of the projection opticalsystem PL, is recovered by the liquid recovery unit 22 via the recoverynozzles 26 and the recovery tube 25. The liquid supply unit 21 and theliquid recovery unit 22 are controlled by the main control system 20. Itis not necessarily indispensable that the exposure apparatus EX isprovided, for example, with the suction pump and the tank of the liquidrecovery unit 22. At least a part of the component can be replaced withthe equipment of the factory or the like in which the exposure apparatusEX is installed.

That is, when the liquid LQ is supplied to the space on the image planeside of the projection optical system PL, the main control system 20outputs the control signals to the liquid supply unit 21 and the liquidrecovery unit 22 respectively to control the supply amount and therecovery amount of the liquid LQ per unit time. According to the controlas described above, the liquid LQ is supplied in a necessary andsufficient amount to the image plane side of the projection opticalsystem PL. In the example shown in FIG. 1, the liquid LQ is recovered byusing, for example, the suction pump, the recovery tube 25, and therecovery nozzles 26 provided over the wafer stage 15. However, there isno limitation thereto. For example, a recovery section (discharge port)for the liquid LQ may be provided around the upper surface of the waferstage 15, and the liquid recovery unit 22 may be used in combinationtherewith.

The exposure beam sensor 27, which measures the uneven illuminance(uneven light amount) or the totalized uneven light amount and the lightamount (radiation amount) of the exposure beam to be radiated onto thewafer stage 15 via the projection optical system PL, is provided on thewafer stage 15 described above. FIG. 3 shows an exemplary structure ofthe exposure beam sensor 27, wherein FIG. 3A shows a perspective view,and FIG. 33 shows a sectional view taken along arrows indicated by aline A-A shown in FIG. 3A. As shown in FIG. 3A, the exposure beam sensor27 includes a chassis 30 having a substantially rectangularparallelepiped shape. The chassis 30 is a casing which is formed of ametal such as aluminum having a high coefficient of thermalconductivity. The chassis 30 has the upper surface 33 which is formedwith an opening 32 and a pinhole 31 as the light-transmitting section.

The pinhole 31, which is formed through the upper surface 33 of thechassis 30, is provided to measure the uneven illuminance or thetotalized uneven light amount of the exposure beam IL radiated via theprojection optical system PL, which has a diameter of about ten totwenty or several tens μm. The opening 32, which is formed through theupper surface 33 of the chassis 30, is designed to have a sizeapproximately equivalent to that of the exposure area (projection areaof the projection optical system PL). An ND filter 34, which has onesurface vapor-deposited, for example, with Cr (chromium) and whichreduces the incoming light beam, is provided in the opening 32. As shownin FIG. 3B, an irradiation irregularity sensor 36 and a dose sensor 37are provided in the chassis 30. Any one of the irradiation irregularitysensor 36 and the dose sensor 37 is provided with a light-receivingelement such as a PIN photodiode. The light amount of the exposure beamcome into the light-receiving surface thereof is detected. In FIG. 3A,reference numeral 35 indicates a wiring for leading, to the outside ofthe exposure beam sensor 27, the detection signals of thelight-receiving elements provided for the irradiation irregularitysensor 36 and the dose sensor 37 (see FIG. 38).

The irradiation irregularity sensor 36 has the areal size of thelight-receiving surface which is set to such an extent that the exposurebeam, which has passed through the pinhole 31, can be received. The dosesensor 37 has the areal size of the light-receiving surface which is setto such an extent that the exposure beam, which is transmitted throughthe ND filter 34 provided in the opening 32, can be received. Thelight-receiving element, which is provided for each of the irradiationirregularity sensor 36 and the dose sensor 37, has the light-receivingsurface which is coated with an AR coat for the ArF laser beam. Therespective light-receiving elements are attached to an electric circuitboard 38 by the aid of support members.

The wiring 35 is connected to the electric circuit board 38. In thisarrangement, the detection signals of the light-receiving elementsprovided for the irradiation irregularity sensor 36 and the dose sensor37 are led to the outside via the wiring 35. The light-receivingelements provided for the irradiation irregularity sensor 36 and thedose sensor 37 respectively may be, for example, any one ofphototransformation elements based on the use of, for example, thephotoelectromotive force effect, the Schottky effect, thephotoelectromagnetic effect, the photoconduction effect, thephotoelectron emission effect, and the pyroelectric effect. The exposurebeam sensor 27 is not limited to the arrangement in which thelight-receiving elements are provided therein. Alternatively, theexposure beam sensor 27 may be constructed such that only alight-receiving system for receiving the exposure beam is providedinside, and the light beam, which is received by the light-receivingsystem, is led to the outside of the chassis 30 by using, for example,an optical fiber or a mirror to effect the photoelectric conversion byusing a photoelectric detector such as a photomultiplier.

When the pinhole 31 provided for the exposure beam sensor 27 is arrangedin the exposure area, and the exposure beam is radiated onto theexposure area, then only the exposure beam, which is included in theradiated exposure beam and which has passed through the pinhole 31, isdetected by the light-receiving element provided for the irradiationirregularity sensor 36. When the exposure beam is detected while movingthe pinhole 31 in the state in which the exposure beam is radiated ontothe exposure area, it is possible to measure the uneven illuminance andthe totalized uneven light amount of the exposure beam in the exposurearea. When the exposure beam is radiated onto the exposure area in astate in which the opening 32 provided for the exposure beam sensor 27is arranged in the exposure area, the exposure beam, which is reduced ordimmed by the ND filter 34, is detected by the light-receiving elementprovided for the dose sensor 37. The light-reducing ratio or theextinction ratio of the ND filter 34 is known. Therefore, it is possibleto measure the light amount of the exposure beam radiated onto theexposure area on the basis of the light-reducing ratio and the result ofthe detection performed by the light-receiving element provided for thedose sensor 37.

The detection signal of the exposure beam sensor 27 as explained aboveis supplied to the main control system 20. The measuring operations forthe uneven illuminance and the light amount are executed, for example,periodically (every time when the wafers W in a lot unit are processedand every time when the reticle R is exchanged). The main control system20 changes the intensity of the exposure beam radiated from the lightsource 1 so that the unevenness is decreased, and the main controlsystem 20 controls the illuminance distribution of the exposure beamradiated onto the image plane side of the projection optical system PL,on the basis of the uneven illuminance and the uneven totalized lightamount measured by using the irradiation irregularity sensor 36 of theexposure beam sensor 27. Further, the main control system 20 determinesthe control parameter to compensate the variation or fluctuation of theoptical characteristic of the projection optical system PL caused by theincidence of the exposure beam on the basis of the light amount of theexposure beam measured by using the light amount sensor 37 of theexposure beam sensor 27. When the wafer W is exposed, the controlparameter is used to control the optical characteristic of theprojection optical system PL by the aid of the lens controller section14. As for the adjustment for the illuminance distribution of theexposure beam radiated onto the image plane side of the projectionoptical system PL, it is possible to apply techniques as disclosed, forexample, in Japanese Patent Application Laid-open No. 10-189427(corresponding to U.S. Pat. No. 5,867,319), Japanese Patent ApplicationLaid-open No. 2002-100561 (corresponding to U.S. Pat. No. 6,771,350),and Japanese Patent Application Laid-open No. 2000-315648 (correspondingto U.S. Pat. Nos. 6,013,401 and 6,292,255). The disclosures of thepatent documents are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

The arrangement of the exposure apparatus EX according to the firstembodiment of the present invention has been explained above. Next, anexplanation will be made about the operation of the exposure apparatusEX constructed as described above. FIG. 4 shows a flow chartillustrating an example of the operation to be performed upon the startof the exposure process by the exposure apparatus according to the firstembodiment of the present invention. The flow chart shown in FIG. 4 isexecuted, for example, when the wafers W in an amount of one lot aresubjected to the exposure process. At the point of the time of thestart, the reticle R is not retained on the reticle stage 13, the waferW 16 is not retained on the wafer holder 16, and the liquid LQ is notsupplied to the image plane side of the projection optical system PL.

Starting from this state, the main control system 20 firstly drives thedriving motor 8 f to arrange, at the outgoing plane CJ of the secondfly's eye lens 7, the minute circular aperture diaphragm 8 e having theminute σ value of the aperture diaphragms 8 a to 8 e arranged in theaperture diaphragm plate 8 (Step S1). When the arrangement of theaperture diaphragm 8 e is completed, the main control system 20 outputsthe control signal to the stage-driving system 19 while monitoring themeasurement result of the laser interferometer 18 to move the waferstage 15 so that the opening 32 (ND filter 34) formed on the chassis 30of the exposure beam sensor 27 is arranged in the exposure area.

When the arrangement of the exposure beam sensor 27 is completed inaccordance with the movement of the wafer stage 15, the main controlsystem 20 outputs the control signal to the light source 1 so that thelight source 1 effects the light emission. The substantially parallellight flux, which is radiated from the light source 1 in accordance withthe light emission of the light source 1, passes through thebeam-shaping optical system 2, and the light flux is shaped into thelight flux having the predetermined cross section. The light fluxsuccessively passes along the interference-reducing section 3, the firstfly's eye lens 4, the vibration mirror 5, and the relay optical system6, and the light flux comes into the second fly's eye lens V.Accordingly, the large number of secondary light sources are formed onthe outgoing plane CJ of the second fly's eye lens 7.

The exposure beam, which is included in the light fluxes from thesecondary light sources and which has passed through the aperturediaphragm 8 e arranged at the outgoing plane CJ of the second fly's eyelens 7, passes through the condenser optical system 10, and the exposurebeam is deflected by the bending mirror 11. In this situation, thereticle R is not retained by the reticle stage 13. Therefore, theexposure beam, which has been deflected by the bending mirror 11,directly comes into the projection optical system PL without passingthrough the reticle R.

In this arrangement, the projection optical system PL is designed tohave the large the numerical aperture NA in order to realize the highresolution. The image of the pattern can be formed on the image planeside even when the angular aperture of the exposure beam directed towardthe image plane side of the projection optical system PL is large in astate in which the liquid LQ is supplied to the image plane side of theprojection optical system PL. However, in this situation, the liquid LQis not supplied to the image plane side of the projection optical systemPL. Therefore, if the aperture diaphragm 8 e having the relatively largeσ value is arranged at the outgoing plane CJ of the second fly's eyelens 7, a part of the exposure beam including the outermost ray issubjected to the total reflection at the end portion of the projectionoptical system PL, which cannot pass through the projection opticalsystem PL.

This situation will be explained with reference to FIG. 45. In FIG. 45,the liquid LQ is supplied to the space between the stage surface 15 aand the optical element LS provided at the end portion of the projectionoptical system PL. The condition, under which the light beam passesthrough the projection optical system PL and the light beam outgoes fromthe end portion PLE on the light-outgoing side of the optical element LSto the liquid, is that the exposure beam (outermost ray) EL is nottotally reflected by the interface between the optical element LS andthe medium existing in the space between the optical element LS and thestage surface 15 a, i.e., the end portion PLE on the light-outgoing sideof the optical element LS. The total reflection condition resides inthat n_(p)·sin θi=n_(L) is satisfied, wherein θi represents the incidentangle of the exposure beam EL into the end portion PLE on thelight-outgoing side, n_(p) represents the refractive index of the endportion PLE on the light-outgoing end of the optical element LS, andn_(L) represents the refractive index of the liquid LQ (medium).Therefore, on condition that the incident angle θi satisfies n_(p)·sinθi<n_(L), the exposure beam EL is refracted from the end portion PLE onthe light-outgoing side toward the liquid, and the exposure beam ELoutgoes at the outgoing angle θo. However, when the liquid LQ is absentin the space between the projection optical system PL and the stagesurface 15 a, the gas having a refractive index n_(G) exists in thespace. Therefore, the condition, under which the total reflection is notcaused, resides in n_(p)·sin θi<n_(G). However, the refractive indexn_(G) of the gas is usually smaller than the refractive index n_(L) ofthe liquid. Therefore, the angle θi, which satisfies this condition, issmaller than that obtained when the liquid exists. As a result, even inthe case of the same incident angle θi, the total reflection isoccasionally caused as shown by a broken line in FIG. 45, when theliquid LQ is absent (illustrated case resides in the total reflectioncritical angle). Therefore, in order to measure the exposure beamwithout allowing the liquid to intervene in the space, it is sometimesnecessary that the angle should be adjusted to be smaller than theincident angle approved when the liquid immersion exposure is performed.

In this embodiment, the angular aperture of the exposure beam directedtoward the image plane side of the projection optical system PL isadjusted (angular aperture is decreased) by arranging the aperturediaphragm 8 e having the minute σ value (for example, 0.25) at theoutgoing plane CJ of the second fly's eye lens 7 in Step S11. Therefore,the exposure beam, which has come into the projection optical system PL,can pass through the projection optical system PL. The exposure beam,which has passed through the projection optical system PL, comes intothe ND filter 34 (FIG. 3) arranged in the exposure area. The exposurebeam is reduced by a predetermined amount, and the exposure beam isdetected by the light-receiving element provided for the dose sensor 37.The detection signal is outputted to the main control system 20 tocalculate the light amount of the exposure beam radiated onto theexposure area by using the light-reducing ratio of the ND filter 34.Accordingly, the light amount of the exposure beam radiated onto theexposure area is measured in the state in which the reticle R is notretained by the reticle stage 13 (Step S12).

Subsequently, the main control system 20 stops the light emission of thelight source 1, and then the control signal is outputted to anunillustrated reticle loader system to export the predetermined reticleR from an unillustrated reticle library. The reticle R is retained onthe reticle stage 13 (Step S13). When the reticle R is retained on thereticle stage 13, the main control system 20 allows the light source 1to effect the light emission again, and the light amount of the exposurebeam passed through the reticle R is measured by using the dose sensor37 (Step S14). Accordingly, it is possible to determine the differencebetween the light amount of the exposure beam radiated onto the exposurearea when the reticle R is retained on the reticle stage 13 and thelight amount of the exposure beam radiated onto the exposure area whenthe reticle R is not retained. The transmittance of the reticle R(incoming light amount into the projection optical system PL) can bedetermined on the basis of the difference.

Subsequently, the main control system 20 outputs the control signal tothe unillustrated reticle loader system to effect the export from thereticle stage 13 and effect the waiting operation. Further, the controlsignal is outputted to the stage-driving system 19 while monitoring themeasurement result of the laser interferometer 18 to move the waferstage 15 so that the pinhole 31 formed for the chassis 30 of theexposure beam sensor 27 is arranged at the predetermined position in theexposure area. When the arrangement of the exposure beam sensor 27 iscompleted in accordance with the movement of the wafer stage 15, themain control system 20 outputs the control signal to the light source 1to allow the light source 1 to effect the light emission. The unevenilluminance of the exposure beam radiated onto the exposure area ismeasured by using the irradiation irregularity sensor 36 while movingthe wafer stage 15 (Step S15).

When the processing as described above is completed, then the maincontrol system 20 outputs the control signal to the light source 1 tochange the intensity and the intensity distribution of the exposure beamon the basis of the measurement results obtained in Steps S14 and S15,or the main control system 20 changes the parameter to adjust theoptical performance of the projection optical system PL by the aid ofthe lens controller section 14 (Step S16). Subsequently, the maincontrol system 20 outputs the control signal to the unillustratedreticle loader so that the reticle R is retained on the reticle stage13. Further, the driving motor 8 f is driven so that the aperturediaphragm 8 e, which is to be arranged at the outgoing plane CJ of thesecond fly's eye lens 7, is changed to any one of the aperturediaphragms 8 a to 8 d for exposing the wafer W. For example, when thezonal illumination is performed, the aperture diaphragm 8 b is arrangedat the outgoing plane CJ of the second fly's eye lens 7 (Step S17).

Subsequently, the main control system 20 outputs the control signal tothe unillustrated wafer loader system to transport the wafer W into theunillustrated chamber of the exposure apparatus EX so that the wafer Wis retained on the wafer holder 16. When the wafer W is retained on thewafer holder 16, the main control system 20 outputs the control signalsto the liquid supply unit 20 and the liquid recovery unit 22.Accordingly, the liquid LQ is supplied to the space on the image planeside of the projection optical system PL (Step S18), and the exposureprocess is performed, in which the pattern formed on the reticle R istransferred onto the wafer W via the projection optical system PL andthe liquid LQ (Step S19). The exposure process is performed for all ofthe wafers W of the amount of one lot. The processing shown in FIG. 4 asexplained above is performed every time when the exposure process isperformed for new lot. The optical performance of the projection opticalsystem PL is adjusted depending on the radiation amount of the exposurebeam with respect to the projection optical system PL by using thecontrol parameter determined in Step S16 during the exposure for thewafers W of the amount of one lot.

For the purpose of convenience of the explanation, the flow chart shownin FIG. 4 has been explained as exemplified by the case in which themeasurement of the light amount based on the use of the dose sensor 37(Step S14) and the measurement of the uneven illuminance based on theuse of the irradiation irregularity sensor 36 (Step S15) arecontinuously performed in the state in which the aperture diaphragm 8 ehaving the minute σ value is arranged without any liquid LQ at theoutgoing plane CJ of the second fly's eye lens 7. However, any one ofthe measurements may be performed through the liquid LQ on the imageplane side of the projection optical system PL. In particular, thecorrect uneven illuminance cannot be measured in some cases under thecondition (condition of the minute σ value of 0.25) different from theactual exposure condition. Therefore, the measurement in Step S15 may beperformed in the state in which the liquid LQ is supplied to the imageplane side of the projection optical system PL (i.e., between Step S18and Step S19) by applying any countermeasure for the liquid immersion tothe irradiation irregularity sensor 36, for example, by performing awaterproof treatment to the pinhole 31.

In the embodiment described above, the uneven illuminance is measured bythe irradiation irregularity sensor 36 after performing the measurementof the light amount based on the use of the dose sensor 37. However, thesteps of exporting and importing the reticle R lower the throughput.Therefore, it is preferable that the light amount is measured by thedose sensor 37 after measuring the uneven illuminance by the irradiationirregularity sensor 36. The reticle R is retracted from the optical pathfor the exposure beam during the measurement of the uneven illuminancebased on the use of the irradiation irregularity sensor 36. However, areticle (simple glass for the measurement), on which no pattern isformed, may be arranged.

In the embodiment described above, the coherence factor (σ of theillumination system) is changed to adjust the angular aperture of theexposure beam directed to the image plane side of the projection opticalsystem PL by changing the aperture diaphragm to be arranged at theoutgoing plane CJ of the second fly's eye lens 7. However, theadjustment of the angular aperture of the exposure beam is not limitedthereto, for which various methods can be used. For example, theadjustment may be performed such that a zoom optical system is arrangedat the upstream stage (on the side of the light source 1) of the secondfly's eye lens 7, and the distribution of the light flux come into thesecond fly's eye lens 7 is changed to change the light flux distributionof the exposure beam at the outgoing plane CJ of the second fly's eyelens 7. In the embodiment described above, the value of the coherencefactor (σ of the illumination system) is set to 0.25. However, there isno limitation thereto. Setting may be made such that the totalreflection is not caused for a part of the exposure beam at the endsurface of the projection optical system PL even in the state in whichliquid LQ is absent on the image plane side of the projection opticalsystem PL, considering the refractive index of the liquid LQ and thenumerical aperture of the projection optical system PL.

In the embodiment described above, the measurement by the irradiationirregularity sensor 36 and the measurement by the dose sensor 37 areperformed in the state in which the liquid LQ is absent on the imageplane side of the projection optical system PL. However, even when theangular aperture of the exposure beam is adjusted, the reflectance atthe lower surface of the projection optical system PL is sometimesdifferent between the state in which the liquid LQ exists on the imageplane side of the projection optical system PL and the state in whichthe liquid LQ is absent. In such a situation, the following procedure isavailable. That is, for example, the exposure beam is radiated in astate in which a reflecting plate having a predetermined reflectance isarranged on the image plane side of the projection optical system PL.The light amount returned from the projection optical system PL ismeasured for the state in which the liquid LQ exists and the state inwhich the liquid LQ is absent respectively by using a reflection amountmonitor as disclosed, for example, in Japanese Patent ApplicationLaid-open No. 2001-144004 (corresponding to U.S. Pat. No. 6,730,925).The difference therebetween is retained as correction information. Themeasurement results of the irradiation irregularity sensor 36 and thedose sensor 37, which are obtained without the liquid LQ, are correctedby using the correction information. The disclosure of Japanese PatentApplication Laid-open No. 2001-144004 (corresponding to U.S. Pat. No.6,730,925) is incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

The first embodiment has been explained for the case in which themeasurement is performed without the liquid LQ by using the irradiationirregularity sensor 36 and the dose sensor 27. However, the measurementwithout the liquid LQ is also applicable to various measuring unitsincluding, for example, a spatial image-measuring unit and a wave frontaberration-measuring unit as described later on. In this case, anoptical (glass) member, which amounts to the liquid LQ, may be arrangedin the space on the image plane side of the projection optical systemPL. When such an optical member is arranged, the measurement can beperformed even without the liquid LQ under a condition approximate tothat of the case in which the space on the image plane side of theprojection optical system PL is filled with the liquid LQ. The wavefront aberration-measuring unit is disclosed, for example, in U.S. Pat.No. 6,650,399 and United States Patent Publication No. 2004/0090606. Thedisclosures thereof are incorporated herein by reference.

As described above, in the first embodiment, the exposure beam come intothe projection optical system PL can be satisfactorily received via thelight-transmitting section of each of the various sensors even when thenumerical aperture of the projection optical system is increased as aresult of the adoption of the liquid immersion method. Further, themeasurement can be performed with the various sensors without beingaffected by the state of the liquid LQ (for example, the temperaturechange, the fluctuation, and the transmittance change), because theexposure beam is received without passing through the liquid LQ.

Second Embodiment

Next, an exposure apparatus according to a second embodiment of thepresent invention will be explained. The overall structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1. However, thestructure of the exposure beam sensor 27 differs. In the firstembodiment, the exposure beam sensor 27 performs the measuring operation(receiving of the exposure beam) without providing the liquid LQ on theimage plane side of the projection optical system PL. However, in thefollowing description, an exposure beam sensor 27 performs the measuringoperation through the liquid LQ on the image plane side of theprojection optical system PL. As shown in FIG. 3, the exposure beamsensor 27 described in the first embodiment is provided with theirradiation irregularity sensor 36 and the dose sensor 37. In thefollowing description, for the purpose of simplification of theexplanation, a case will be principally exemplified and explained by wayof example, in which the present invention is applied to an irradiationirregularity sensor provided for the exposure beam sensor 27. However,it is a matter of course that the present invention is also applicableto the dose sensor and the spatial image-measuring unit as describedlater on.

FIG. 5 shows a schematic arrangement of the irradiation irregularitysensor provided for the exposure apparatus according to the secondembodiment of the present invention, wherein FIG. 5A shows a sectionalview, and FIG. 5B shows a perspective view illustrating a plano-convexlens provided for the irradiation irregularity sensor. As shown in FIG.5A, the irradiation irregularity sensor 40, which is provided for theexposure apparatus of this embodiment, is constructed to include theplano-convex lens 41 and a light-receiving element 42.

As shown in FIGS. 5A and 5B, the plano-convex lens 41 is an optical lenswhich is formed with a flat section 41 a and a curved section 41 bhaving a predetermined curvature. This embodiment is based on the use ofthe light beam of the ArF excimer laser light source in the vacuumultraviolet region as the exposure beam in the same manner as the firstembodiment. Therefore, for example, synthetic quartz or fluorite is usedas the material for the plano-convex lens 41. A light-shielding section43 is formed on the flat section 41 of the plano-convex lens 41 byvapor-depositing a metal such as Cr (chromium) onto the entire surfaceexcept for a central portion. The metal such as Cr (chromium) is notvapor-deposited on the central portion of the flat section 41 a.Accordingly, a light-transmitting section 44, which has a diameter ofabout ten to twenty or several tens μm, is formed.

The plano-convex lens 41, which is constructed as described above, isattached to the wafer stage 15 so that the flat section 41 a formed withthe light-shielding section 43 is directed toward the projection opticalsystem PL, and the upper surface (upper surface of the light-shieldingsection 43) is coincident with the upper surface 15 a of the wafer stage15. The light-receiving element 42 is attached to the wafer stage 15 sothat the light-receiving surface 42 a is directed toward the curvedsection 41 b of the plano-convex lens 41, and an approximately centralportion of the light-receiving surface 42 a is arranged on the opticalaxis of the plano-convex lens 41. The light-receiving surface 42 a ofthe light-receiving element 42 is coated with an AR coat for the ArFlaser beam.

For the purpose of convenience of the explanation, it is assumed thatthe plano-convex lens 41 and the light-receiving element 42 are attachedto the wafer stage 15. However, it is preferable that these componentsare attached in a chassis which is similar to the chassis 30 shown inFIG. 3, and the chassis is provided on the wafer stage 15. In the caseof such an arrangement, the plano-convex lens 41 is attached to thechassis so that the upper surface of the plano-convex lens 41 (uppersurface of the light-shielding section 43) is coincident with the uppersurface of the chassis. Further, the chassis is attached to the waferstage 15 so that the upper surface of the chassis is coincident with theupper surface 15 a of the wafer stage 15.

Even in any one of the case in which the plano-convex lens 41 isattached to the wafer stage 15 and the case in which the plano-convexlens 41 is attached to the chassis similar to the chassis 30 shown inFIG. 3, a waterproof (liquid-proof) countermeasure is applied, forexample, by a seal member so that the liquid LQ on the wafer stage 15does not make inflow into the irradiation irregularity sensor 40.Therefore, even when the liquid LQ is supplied to the space between theprojection optical system PL and the wafer stage 15 when the irradiationirregularity sensor 40 is arranged under the projection optical systemPL (in the −Z direction) as shown in FIG. 5A, the liquid LQ does notmake inflow into the irradiation irregularity sensor 40.

Therefore, the measurement of the uneven illuminance of the exposurebeam or the uneven totalized light amount of the exposure beam based onthe use of the irradiation irregularity sensor 40 of this embodiment canbe performed in the state in which the liquid LQ is supplied to thespace between the projection optical system PL and the upper surface 15a of the wafer stage 15 (piano-convex lens 41), while the illuminationcondition for the illumination optical system IS is set to theillumination condition to be established when the exposure process isperformed for the wafer W. The exposure beam, which has come into theprojection optical system PL, passes through the projection opticalsystem PL to come into the liquid LQ without being totally reflected atthe end portion of the projection optical system PL in the state inwhich the liquid LQ is supplied to the space between the projectionoptical system PL and the upper surface 15 a of the wafer stage 15.

As shown in FIG. 5A, the exposure beam, which is included in theexposure beam come into the liquid LQ and which has come into thelight-shielding section 43, is shielded. Only the exposure beam, whichhas come into the pinhole-shaped light-transmitting section 44, comesinto the plano-convex lens 41 from the flat section 41 a. In thisarrangement, the refractive index of the plano-convex lens 41 isapproximately equivalent to the refractive index of the liquid LQ, orthe refractive index of the plano-convex lens 41 is higher than therefractive index of the liquid LQ. Therefore, even when the exposurebeam, which has come into the light-transmitting section 44, has a largeincident angle, the exposure beam, which has come into thelight-transmitting section 44, comes into the plano-convex lens 41without being totally reflected by the flat section 41 a of theplano-convex lens 41 exposed in the light-transmitting section 44. Theexposure beam, which has come into the plano-convex lens 41, iscollected by the curved section 41 b formed for the plano-convex lens41, and then the exposure beam comes into the light-receiving surface 41a. The exposure beam is received by the light-receiving element 42.

As described above, in this embodiment, the light-shielding section 43and the light-transmitting section 44 are formed on the flat section 41a of the plano-convex lens 41, and the exposure beam, which has passedthrough the light-transmitting section 44, is allowed to directly comeinto the plano-convex lens 41 having the high refractive index withoutpassing through the gas. Therefore, even when the exposure beam havingthe large incident angle comes into the light-transmitting section 44,the exposure beam can be incorporated into the plano-convex lens 41without being totally reflected. Further, the exposure beam, which hascome into the plano-convex lens 41, is collected by the curved section41 b, and the exposure beam is introduced into the light-receivingsurface 42 a of the light-receiving element 42. Therefore, even when theexposure beam, which has come into the light-transmitting section 44,has the large incident angle, the exposure beam can be received by thelight-receiving element 42.

In the case of the irradiation irregularity sensor 40 shown in FIG. 5,the metal such as Cr (chromium) is vapor-deposited onto the flat section41 a except for the central portion of the plano-convex lens 41 to formthe light-shielding section 43 and the light-transmitting section 44.Therefore, as shown in FIG. 5A, the light-transmitting section 44 isconsequently formed as a recess. When the liquid LQ, which is suppliedto the projection optical system PL, is always circulated by the liquidsupply unit 21 and the liquid recovery unit 22, a possibility is assumedsuch that the flow of the liquid LQ may be disturbed due to the presenceof the light-transmitting section 44. Further, it is feared that thebubble may remain in the light-transmitting section 44 when the supplyof the liquid LQ onto the plano-convex lens 41 is started. Anirradiation irregularity sensor shown in FIG. 6 described below improvesthis embodiment in relation to this point.

FIG. 6 shows a modified embodiment of the irradiation irregularitysensor provided for the exposure apparatus according to the secondembodiment of the present invention, wherein FIG. 6A shows a sectionalview, and FIG. 6B shows a perspective view illustrating a plano-convexlens provided for the irradiation irregularity sensor. The irradiationirregularity sensor 40 shown in FIG. 6 differs in that the plano-convexlens 45 is provided in place of the plano-convex lens 41 provided forthe irradiation irregularity sensor 40 shown in FIG. 5. As shown in FIG.6, the plano-convex lens 45 has a flat section 45 a and a curved section45 b which are formed in the same manner as the flat section 41 a andthe curved section 41 b formed for the plano-convex lens 41. However,the plano-convex lens 45 differs in that the flat section 45 a is notflat over the entire surface, and a projection 46 having a flat upperportion is formed in the vicinity of the center of the flat section 45a.

The light-shielding section 43 is formed on the flat section 45 a byvapor-depositing a metal such as Cr (chromium) except for the projection46. The projection 46, which is formed at the central portion of theflat section 45 a, has the height which is designed to be approximatelythe same as the thickness of the light-shielding section 43. In otherwords, in the case of the illuminance sensor 40 shown in FIG. 6, theprojection 46 is formed as the pinhole-shaped light-transmitting section44. Accordingly, as shown in FIG. 6, even when the liquid LQ is suppliedto the space between the projection optical system PL and the waferstage 15 (plane-convex lens 45) in a state in which the irradiationirregularity sensor 40 is arranged under the projection optical systemPL (in the −Z direction), then the liquid LQ does not flow into thelight-transmitting section 44, and the flow of the liquid LQ is notdisturbed. Further, no bubble remains at the light-transmitting section44. Therefore, when the irradiation irregularity sensor 40 constructedas shown in FIG. 6 is used, it is possible to perform the more correctmeasurement.

In the second embodiment, the projection 46 is formed integrally withthe plano-convex lens 45. However, the projection 46 and theplano-convex lens 45 may be formed separately. Alternatively, theprojection 46 and the plano-convex lens 45 may be formed of differentsubstances. In this case, those usable as the substance for forming theprojection 46 include such substances that the exposure beam can betransmitted therethrough, the refractive index of the substance isapproximately equivalent to the refractive index of the material for theplano-convex lens 45, or the refractive index of the substance is higherthan the refractive index of the liquid LQ, and the refractive index ofthe substance is lower than the refractive index of the material for theplano-convex lens 45.

Third Embodiment

Next, an exposure apparatus according to a third embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1, in the samemanner as in the second embodiment described above. However, thestructure of the exposure beam sensor 27 differs. Also in thisembodiment, an explanation will be principally made about an irradiationirregularity sensor provided for the exposure beam sensor 27.

FIG. 7 shows a schematic arrangement of the irradiation irregularitysensor provided for the exposure apparatus according to the thirdembodiment of the present invention, wherein FIG. 7A shows a sectionalview, and FIG. 7B shows a perspective view illustrating an apertureplate and a plano-convex lens provided for the irradiation irregularitysensor. As shown in FIG. 7A, the irradiation irregularity sensor 50provided for the exposure apparatus of this embodiment is constructed toinclude an upper plate 51, the plano-convex lens 52, and alight-receiving element 53.

As shown in FIGS. 7A and 7B, the upper plate 51 is provided with aparallel flat plate 54 composed of synthetic quarts or fluorite whichhas a high transmittance with respect to the light beam of the ArFexcimer laser light source in the vacuum ultraviolet region. Alight-shielding section 55 is formed on one surface of the parallel flatplate 54 by vapor-depositing a metal such as Cr (chromium) onto theentire surface except for a central portion. The central portion, onwhich the metal such as Cr (chromium) is not vapor-deposited, is acircular light-transmitting section 56. The plano-convex lens 52 is anoptical lens composed of synthetic quartz or fluorite formed with a flatsection 52 a and a curved section 52 b having a predetermined curvaturein the same manner as the plano-convex lens 41 shown in FIG. 5.

The upper plate 51 is attached to make abutment against the uppersurface 15 a of the wafer stage 15 with the surface formed with thelight-shielding section 55 being directed downwardly. The plano-convexlens 52 is attached to make abutment against (make tight contact with)the light-shielding section 55 of the upper plate 51 with the flatsection 52 a being directed toward the projection optical system PL. Thelight-receiving element 53 is equivalent to the light-receiving element42 shown in FIG. 5. The light-receiving element 53 is attached to thewafer stage 15 so that the light-receiving surface 53 a is directedtoward the curved section 52 b of the plano-convex lens 52, and theapproximately central portion of the light-receiving surface 53 a isarranged on the optical axis of the plano-convex lens 52.

The upper plate 51, the plano-convex lens 52, and the light-receivingelement 53 may be attached in a chassis similar to the chassis 30 shownin FIG. 3 in the same manner as in the second embodiment, and thechassis may be provided on the wafer stage 15. In the case of such anarrangement, the upper plate 51 is attached while allowing thelight-shielding section 55 to make abutment against the chassis, and thechassis is attached to the wafer stage 15 so that the upper surface ofthe chassis is coincident with the upper surface 15 a of the wafer stage15. A waterproof countermeasure is applied with a seal member or thelike for the upper plate 51 between the upper plate 51 and the uppersurface of the wafer stage 15 or the upper surface of the chassis.

In the case of the irradiation irregularity sensor 50 constructed asdescribed above, the upper plate 51 serves to avoid any invasion of theliquid LQ into the irradiation irregularity sensor 50. Even when theirradiation irregularity sensor 50 of this embodiment is used, then theillumination condition of the illumination optical system IS is set tothe illumination condition to be established when the exposure processis performed for the wafer W, and the measurement can be performed forthe uneven illuminance or the like in the state in which liquid LQ issupplied to the space between the projection optical system PL and thewafer stage 15.

The exposure beam, which has come into the projection optical system PLin the state in which the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 15 a of the waferstage 15, is not totally reflected at the end portion of the projectionoptical system PL, and the exposure beam passes through the projectionoptical system PL to come into the liquid LQ. The refractive index ofthe parallel flat plate 54 provided for the upper plate 51 isapproximately equivalent to the refractive index of the liquid LQ, orthe refractive index is higher than the refractive index of the liquidLQ. Therefore, the exposure beam, which has passed through the liquidLQ, comes into the upper plate 51. The light beam from thelight-transmitting section 56 formed through the upper plate 51 comesinto the plano-convex lens 52. The exposure beam, which has come intothe plano-convex lens 52, is collected by the curved section 52 b formedfor the plano-convex lens 52. The exposure beam is guided to thelight-receiving surface 53 a, and the exposure beam is received by thelight-receiving element 53.

In this embodiment, the flat section 52 a of the plano-convex lens 52 isin contact with the surface on which the light-shielding section 55 ofthe upper plate 51 is formed. Therefore, the light beam from thelight-transmitting section 56 can be introduced into the light-receivingelement 53 by the plano-convex lens 52 without passing through the gas.With reference to FIG. 7, when the space is consequently formed at thelight-transmitting section 56 between the lower surface of the parallelflat plate 54 and the upper surface of the plano-convex lens 52 due tothe thickness of the light-shielding section (film) formed on onesurface of the parallel flat plate 54, a light-transmissive medium otherthan the gas, which includes, for example, liquid, supercritical fluid,paste, and solid, may be intervened in the space of thelight-transmitting section 56 between the light-transmitting section andthe light-collecting member, for example, in a form of thin film.Alternatively, an adhesive, through which the exposure beam istransmissive, can be used to join the parallel flat plate 54 and theplano-convex lens 52 to allow the adhesive to intervene in the space ofthe light-transmitting section 56 as well. In this arrangement, it isdesirable that the refractive index of the substance intervened in thelight-transmitting section 56 with respect to the exposure beam isapproximately equivalent to the refractive indexes of the plano-convexlens 52 and the parallel flat plate 54. Further, a plano-convex lens 57shown in FIG. 8 may be provided in place of the plano-convex lens 52.FIG. 8 shows a perspective view illustrating another example of theplano-convex lens provided for the irradiation irregularity sensorprovided for the exposure apparatus according to the third embodiment ofthe present invention. The plano-convex lens 57 shown in FIG. 8 isformed with a flat section 57 a and a curved section 57 b in the samemanner as the plano-convex lens 52 shown in FIG. 7. However, theplano-convex lens 57 differs in that the flat section 57 a is not flatover the entire surface, and a projection 58 having a flat upper portionis formed in the vicinity of the center of the flat section 57 a.

The height of the projection 58 is set to be approximately the same asthe thickness of the light-shielding section 55 formed for the upperplate 51. The diameter of the projection 58 is set to be approximatelythe same as the diameter of the light-transmitting section 56 formed forthe upper plate 51. When the flat section 57 a of the plano-convex lens57 constructed as described above is in contact with the surface of theupper plate 51 formed with the light-shielding section 55, theprojection 58 is fitted to the light-transmitting section 56 formed forthe upper plate 51. Accordingly, the exposure beam, which is included inthe exposure beam come into the parallel flat plate 54 of the upperplate 51 and which has come into the light-transmitting section 56,passes through the light-transmitting section 56 so that the exposurebeam comes into the plano-convex lens 57 from the upper surface of theprojection 58. In FIG. 8, the projection 58 is formed integrally withthe plano-convex lens 57. However, the projection 58 and theplano-convex lens 57 may be formed separately. Alternatively, theprojection 58 and the plano-convex lens 57 may be formed of differentsubstances. In this case, it is desirable that the substance for formingthe projection 58 is such a substance that the exposure beam can betransmitted therethrough, and the substance has the refractive indexapproximately equivalent to the refractive indexes of the material forthe parallel flat plate 54 and the material for the plano-convex lens57.

This embodiment is constructed such that the light-shielding section 55is formed on the bottom surface side of the parallel flat plate 54 toallow the plano-convex lens 52 (57) to make the abutment. However, thelight-shielding section 55 may be formed at the flat section 52 a (57 a)of the plano-convex lens 52 (57) to allow the parallel flat plate 54 tomake the abutment.

Fourth Embodiment

Next, an exposure apparatus according to a fourth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1, in the samemanner as in the second and third embodiments described above. However,the structure of the exposure beam sensor 27 differs. Also in thisembodiment, an explanation will be principally made about an irradiationirregularity sensor provided for the exposure beam sensor 27. FIG. 9shows a sectional view illustrating a schematic arrangement of theirradiation irregularity sensor provided for the exposure apparatusaccording to the fourth embodiment of the present invention. As shown inFIG. 9, the irradiation irregularity sensor 60 provided for the exposureapparatus of this embodiment is constructed to include a parallel flatplate 61, a plano-convex lens 62, and a light-receiving element 63.

The parallel flat plate 61 is composed of synthetic quartz or fluoritehaving a high transmittance with respect to the light beam of the ArFexcimer laser light source in the vacuum ultraviolet region. Theparallel flat plate 61 is attached to the upper surface 33 of thechassis 30 so that the pinhole 31 formed for the chassis 30 shown inFIG. 3 is covered therewith. A waterproof countermeasure is applied tothe parallel flat plate 61 by a seal member or the like between theparallel flat plate 61 and the upper surface 33 of the chassis 30 sothat the liquid LQ, which is supplied to the image plane side of theprojection optical system PL, does not make inflow into the irradiationirregularity sensor 60 via the pinhole 31.

The plano-convex lens 62 is an optical lens composed of synthetic quartzor fluorite having its diameter designed to be approximately equivalentto or slightly smaller than the diameter of the pinhole 31. Theplano-convex lens 62 has its flat section which is stuck to the parallelflat plate 61, and thus the plano-convex lens 62 is arranged in thepinhole 31. The light-receiving element 63 is similar to thelight-receiving element 42 shown in FIG. 5. The light-receiving element63 is attached in the chassis 30 so that the light-receiving surface 63a is directed toward the curved section of the plano-convex lens 62, andan approximately central portion of the light-receiving surface 63 a isarranged on the optical axis of the plano-convex lens 62. The areal sizeof the light-receiving surface 63 a of the light-receiving element 42may be appropriately changed depending on the width of the light flux ofthe exposure beam come thereinto.

Also in the case of the irradiation irregularity sensor 60 of thisembodiment, the measurement can be performed, for example, for theuneven illuminance in the state in which the liquid LQ is supplied tothe space between the projection optical system PL and the upper surface33 of the chassis 30, while the illumination condition of theillumination optical system IS is set to the illumination condition tobe established when the exposure process is performed for the wafer W.The exposure beam, which has come into the projection optical system PLin the state in which the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 33 of the chassis 30,is not totally reflected at the end portion of the projection opticalsystem PL, and the exposure beam passes through the projection opticalsystem PL to come into the liquid LQ.

The refractive indexes of the parallel flat plate 61 and theplano-convex lens 62 are approximately equivalent to the refractiveindex of the liquid LQ, or the refractive indexes of the parallel flatplate 61 and the plano-convex lens 62 are higher than the refractiveindex of the liquid LQ. Therefore, the exposure beam, which is includedin the exposure beam come into the parallel flat plate 61 through theliquid LQ and which is directed toward the pinhole 31, is allowed tocome into the plano-convex lens 62 and collected. The exposure beam isintroduced into the light-receiving surface 63 a, and the exposure beamis received by the light-receiving element 63. As described above, alsoin this embodiment, the exposure beam, which comes from the projectionoptical system PL into the liquid LQ, does not pass through the gasuntil the exposure beam outgoes from the plano-convex lens 62.Therefore, even when the exposure beam having a large incident anglecomes into the pinhole 31, the exposure beam can be incorporated intothe plano-convex lens 62 without being totally reflected. Further, theexposure beam can be received by the light-receiving element 63. Whenthe invasion of the liquid LQ from the surrounding of the plano-convexlens 62 can be avoided, it is enough that the parallel flat plate 61 isdispensed with.

In the example shown in FIG. 9, the plano-convex lens 62 is arranged inthe pinhole 31, which is stuck to the parallel flat plate 61 attachedonto the chassis 30. However, the diameter of the plano-convex lens 62is approximately equivalent to that of the pinhole 31, i.e., ten totwenty or several tens μm. Therefore, it is sometimes difficult to dealwith the Plano-convex lens 62. In such a situation, it is preferablethat a convex lens, which is similar to the plano-convex lens 62, isintegrally formed on the parallel flat plate 61, and the parallel flatplate 61 is attached onto the chassis 30 so that the convex lens isarranged in the pinhole 31. When the thickness of the upper plate of thechassis 30 is extremely thin, it is also appropriate that a largeplano-convex lens is arranged on the lower surface of the chassis 30.Also in this case, the light beam from the pinhole 31 can be collectedto arrive at the light-receiving element in the same manner as in FIG.7A.

Fifth Embodiment

Next, an exposure apparatus according to a fifth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1, in the samemanner as in the second and fourth embodiments described above. However,the structure of the exposure beam sensor 27 differs. Also in thisembodiment, an explanation will be principally made about an irradiationirregularity sensor provided for the exposure beam sensor 27. FIG. 10shows a sectional view illustrating a schematic arrangement of theirradiation irregularity sensor provided for the exposure apparatusaccording to the fifth embodiment of the present invention. As shown inFIG. 10, the irradiation irregularity sensor 70 provided for theexposure apparatus of this embodiment is constructed to include aplano-convex lens 71 and a light-receiving element 72.

The plano-convex lens 71 is composed of synthetic quartz or fluoritehaving a high transmittance with respect to the light beam of the ArFexcimer laser light source in the vacuum ultraviolet region, which hasthe diameter designed to be larger than the diameter of the pinhole 31formed for the chassis 30 shown in FIG. 3. The plano-convex lens 71 hasa flat section 71 a which is stuck to the inner portion of the chassis30 at the position of formation of the pinhole 31. Accordingly, a stateis given, in which the pinhole 31 is closed by the plano-convex lens 71.It is possible to avoid the invasion of the liquid LQ into theirradiation irregularity sensor 70 via the pinhole 31. When theplano-convex lens 71 is stuck to the inner portion of the chassis 30, itis preferable to apply a waterproof countermeasure by a seal member orthe like.

The light-receiving element 72 is similar to the light-receiving element42 shown in FIG. 5. The light-receiving element 72 is attached in thechassis 30 so that the light-receiving surface 72 a is directed towardthe curved section 71 b of the plano-convex lens 72, and anapproximately central portion of the light-receiving surface 72 a isarranged on the optical axis of the plano-convex lens 71. Also in thecase of the irradiation irregularity sensor 70 of this embodiment, themeasurement can be performed, for example, for the uneven illuminance inthe state in which the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 33 of the chassis 30,while the illumination condition of the illumination optical system ISis set to the illumination condition to be established when the exposureprocess is performed for the wafer W.

The exposure beam, which comes into the projection optical system PL inthe state in which the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 33 of the chassis 30,is not totally reflected at the end portion of the projection opticalsystem PL, and the exposure beam passes through the projection opticalsystem PL to come into the liquid LQ. The refractive index of theplano-convex lens 71 is approximately equivalent to the refractive indexof the liquid LQ, or the refractive index of the plano-convex lens 71 ishigher than the refractive index of the liquid LQ. Therefore, theexposure beam, which is included in the exposure beam come into theliquid LQ and which comes into the pinhole 31, is allowed to come intothe plano-convex lens 71 and collected. The exposure beam is introducedinto the light-receiving surface 72 a, and the exposure beam is receivedby the light-receiving element 72.

As described above, in this embodiment, the exposure beam, which hascome into the liquid LQ from the projection optical system PL and whichhas passed through the pinhole 31, directly comes into the plano-convexlens 71 having the high refractive index without passing through thegas. Therefore, even when the exposure beam having a large incidentangle comes into the pinhole 31, the exposure beam can be incorporatedinto the plano-convex lens 71 without being totally reflected. Further,the exposure beam can be received by the light-receiving element 72.

In this embodiment, a possibility is assumed such that the flow of theliquid LQ may be disturbed due to the presence of the pinhole 31, andthe liquid LQ may be excited or boiled due to the occurrence of thevortex flow to generate the bubble in the liquid LQ, in the same manneras in the second embodiment. In order to avoid such an inconvenience,the plano-convex lens 57 shown in FIG. 8 can be used as the plano-convexlens 71, and the plano-convex lens 57 can be stuck to the inner portionof the chassis 30 so that the projection 58, which is formed on the flatsection 57 a, is fitted to the pinhole 31. Alternatively, a substance,through which the exposure beam is transmissive, may be intervened inthe pinhole 31.

The second to fifth embodiments have been explained above as exemplifiedby the case in which the plano-convex lens 41, 45, 52, 57, 62, 71 andthe light-receiving element 42, 53, 63, 72 are arranged separately.However, in order to maximally avoid the absorption of the exposure beamby oxygen or the like, the plano-convex lens 41, 45, 52, 57, 62, 71 andthe light-receiving element 42, 53, 63, 72 may be in contact with eachother. The foregoing embodiments have been explained as exemplified bythe plano-convex lens 41, 45, 52, 57, 62, 71 as the light-collectingmember. However, other than the above, it is possible to use, forexample, DOE (diffractive optical element), small lens array, Fresnellens, and reflecting mirror.

Sixth Embodiment

Next, an exposure apparatus according to a sixth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is also constructed inapproximately the same manner as the exposure apparatus shown in FIG. 1.However, the structure of the exposure beam sensor 27 differs. Theexposure beam sensor 27 provided for the exposure apparatus of thisembodiment performs the measuring operation through the liquid LQ on theimage plane side of the projection optical system PL, in the same manneras in the second to fifth embodiments described above. However, thisembodiment will be principally explained as exemplified by a dose sensorprovided for the exposure beam sensor 27. It is a matter of course thatthis embodiment is also applicable to the irradiation irregularitysensor described above and the spatial image-measuring unit as describedlater on.

FIG. 11 shows a schematic arrangement of the dose sensor provided forthe exposure apparatus according to the sixth embodiment of the presentinvention. As shown in FIG. 11A, the dose sensor 80 provided for theexposure apparatus of this embodiment is constructed to include alight-collecting plate 81 and a light-receiving element 82. Thelight-collecting plate 81 is composed of synthetic quartz or fluoritehaving a high transmittance with respect to the light beam of the ArFexcimer laser light source in the vacuum ultraviolet region. As shown inFIGS. 11A and 11B, a microlens array 83 is formed on one surface(surface to make no contact with the liquid LQ) 81 a of thelight-collecting plate 81.

The microlens array 83 is an optical element which is composed of alarge number of circular microlenses having the positive refractivepower arranged, for example, in the two directions perpendicular to oneanother. The microlens array 83 shown in FIG. 11 is illustrated by wayof example in every sense. The shape of the microlens is not limited tothe circular shape, which may be a square shape. The arrangement is notlimited to the arrangement in the two perpendicular directions, whichmay be a dense arrangement. The microlens array 83 is constructed, forexample, by performing the etching treatment to one surface of aparallel plane glass plate to form a group of microlenses.

The light-collecting plate 81 is provided in the opening 32 formed forthe chassis 30 so that the flat surface 81 b, which is opposed to thesurface 81 a formed with the microlens array 83, is directed toward theprojection optical system PL (in the +Z direction), and the surface 81 bis coincident with the upper surface 33 of the chassis 30 shown in FIG.3. In this embodiment, the ND filter 34 shown in FIG. 3 is not provided.Another arrangement is also available such that the microlens array 83is stuck to the ND filter 34, or the ND filter is provided between themicrolens array 83 and the light-receiving element 82. A waterproofcountermeasure is applied between the light-collecting plate 81 and thechassis 30 so that the liquid LQ, which is supplied to the image planeside of the projection optical system PL, does not make inflow into thechassis 30.

The light-receiving element 82 is arranged so that the light-receivingsurface 82 a is directed toward the light-collecting plate 81, and anapproximately central portion of the light-receiving surface 82 a ispositioned just under the approximately central portion of thelight-collecting plate 81 (in the −Z direction). The light-receivingelement 82 is attached closely to the light-collecting plate 81 so thatmost of the light flux collected by the light-collecting plate 81 isreceived by the light-receiving surface 82 a. An AR coat for the ArFlaser beam is applied to the light-receiving surface 82 a of thelight-receiving element 82.

When the light amount of the exposure beam radiated onto the exposurearea is measured by using the dose sensor 80 of this embodiment, themeasurement can be performed in such a state that the illuminationcondition of the illumination optical system IS is set to theillumination condition to be established when the exposure process isperformed for the wafer W, and the liquid LQ is supplied to the spacebetween the projection optical system PL and the upper surface 33 of thechassis 30, unlike the measurement to be performed with the dose sensor37 of the first embodiment. The exposure beam comes into the projectionoptical system PL in the state in which the liquid LQ is supplied to thespace between the projection optical system PL and the upper surface 33of the chassis 30. The exposure beam passes through the projectionoptical system PL to come into the liquid LQ, although even the outmostray is not totally reflected at the end portion of the projectionoptical system PL.

The refractive index of the light-collecting plate 81 is approximatelyequivalent to the refractive index of the liquid LQ, or the refractiveindex of the light-collecting plate 81 is higher than the refractiveindex of the liquid LQ. Therefore, the exposure beam, which has comeinto the liquid LQ, comes into the light-collecting plate 81. Thewavefront of the exposure beam is two-dimensionally divided by the largenumber of microlenses which form the microlens array 83 formed on thesurface 81 a of the light-collecting plate 81, and the wavefront isconverged by the refractive function of the microlenses. After that, therespective divided wavefronts have come into the light-receiving surface82 a of the light-receiving element 82 and received.

As described above, also in this embodiment, the exposure beam, whichcomes into the liquid LQ from the projection optical system PL, does notpass through the gas until the exposure beam outgoes from thelight-collecting plate 81. Therefore, even when the exposure beam havinga large incident angle comes into the light-collecting plate 81, theexposure beam can be incorporated into the light-collecting plate 81without being totally reflected. Further, the exposure beam can bereceived by the light-receiving element 82. As for the dose sensor, theareal size of the opening 32 is large. Therefore, if an arrangement isadopted such that any single lens is provided for the opening 32 tocollect the incoming light beam as with the plano-convex lens 41, 52, 71used for the irradiation irregularity sensor explained in the second,third, and fifth embodiments, then the dose sensor is consequentlylarge-sized, and any inconvenience arises when the sensor is provided onthe wafer stage 15 shown in FIG. 1. In this embodiment, the microlensarray 82 is used without using the single lens as described above. Thus,it is possible to realize the small size and the light weight of thedose sensor 80.

The foregoing explanation has been made for the case in which themicrolens array 83 is formed on one surface 81 a of the light-collectingplate 81. However, it is also preferable to use a light-collecting platein which microlens arrays are formed on both surfaces (surfaces 81 a, 81b). Alternatively, a fly's eye lens may be used in place of themicrolens array. When the microlens array 83 is formed on only onesurface 81 a of the light-collecting plate 81, apertures 84 may beformed and used corresponding to the large number of respectivemicrolenses for forming the microlens array 83, on the surface 81 b ofthe light-collecting plate 81 directed toward the projection opticalsystem PL as shown in FIG. 12. FIG. 12 shows a perspective viewillustrating an exemplary arrangement of the light-collecting plate inwhich the apertures corresponding to the microlens array are formed.

The apertures 84 shown in FIG. 12 are formed, for example, such that ametal such as Cr (chromium) is vapor-deposited onto the entire surfaceof the surface 81 b, and the portions corresponding to the respectivemicrolenses are subjected to the etching. The aperture 84 functions as adiaphragm to restrict the amount of the light flux come into each of themicrolenses. Therefore, it is possible to provide the functionequivalent to that of the ND filter. In this embodiment, theillumination condition of the illumination optical system IS is set tothe illumination condition to be established when the exposure processis performed for the wafer W. Therefore, in view of the protection ofthe light-collecting plate 81 and the light-receiving element 82, it isdesirable to form the apertures 84. In this embodiment, the explanationhas been made about the dose sensor 80 provided for the exposure beamsensor 27. However, for example, this arrangement is also applicable tothe irradiation irregularity sensor by using the light-collecting plateformed with the microlens array in place of the plano-convex lens 41shown in FIG. 5.

Seventh Embodiment

Next, an exposure apparatus according to a seventh embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1. However, thestructure of the exposure beam sensor 27 differs. The exposure beamsensor 27 provided for the exposure apparatus of this embodimentperforms the measuring operation through the liquid LQ on the imageplane side of the projection optical system PL, in the same manner as inthe second to fifth embodiments described above. However, thisembodiment will be principally explained about a dose sensor providedfor the exposure beam sensor 27.

FIG. 13 shows a schematic arrangement of the dose sensor provided forthe exposure apparatus according to the seventh embodiment of thepresent invention. As shown in FIG. 13, the dose sensor 85 provided forthe exposure apparatus of this embodiment is constructed to include adiffusion plate 86 and a light-receiving element 87. The diffusion plate86 is provided in the opening 32 formed for the chassis 30. Thediffusion plate 86 is composed of synthetic quartz or fluorite. Thediffusion plate 84 has a surface 86 a formed with minute irregularitiesor concave/convex portions and a flat surface 86 b. The diffusion plate86 is provided in the opening 32 so that the surface 86 b is directedtoward the projection optical system PL (in the +Z direction), and thesurface 86 b is coincident with the upper surface 33 of the chassis 30shown in FIG. 3. A waterproof countermeasure is applied with a sealmember or the like between the diffusion plate 86 and the chassis 30.The light-receiving element 87 is arranged so that the light-receivingsurface 87 a is directed toward the diffusion plate 86, and anapproximately central portion of the light-receiving surface 87 a ispositioned just under an approximately central portion of the diffusionplate 86 (in the −Z direction). The light-receiving element 87 isarranged in a state in which the light-receiving surface 87 a isdisposed closely to the diffusion plate 86. An AR coat for the ArF laserbeam is applied to the light-receiving surface 87 a of thelight-receiving element 87.

When the light amount of the exposure beam radiated onto the exposurearea is measured by using the dose sensor 85 of this embodiment, themeasurement is performed in such a state that the illumination conditionof the illumination optical system IS is set to the illuminationcondition to be established when the exposure process is performed forthe wafer W, and the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 33 of the chassis 30,in the same manner as in the sixth embodiment. When the exposure beamcomes into the projection optical system PL in this state, the exposurebeam passes through the projection optical system PL, while even theoutmost ray is not totally reflected at the end portion of theprojection optical system PL, and the exposure beam comes into theliquid LQ. Further, the exposure beam comes into the diffusion plate 86having the refractive index which is approximately equivalent to orhigher than the refractive index of the liquid LQ. The exposure beam,which comes into the diffusion plate 86, is diffused by the surface 86 aformed with the minute irregularities when the exposure beam outgoesfrom the diffusion plate 86. After that, the exposure beam has come intothe light-receiving surface 87 a of the light-receiving element 87 andreceived.

As described above, also in this embodiment, the exposure beam, whichcomes into the liquid LQ from the projection optical system PL, does notpass through the gas until the exposure beam outgoes from the diffusionplate 86. Therefore, even when the exposure beam having a large incidentangle comes into the diffusion plate 86, the exposure beam is nottotally reflected. Further, when the exposure beam outgoes from thediffusion plate 86, the exposure beam is diffused. Accordingly, a largeramount of the exposure beam having the large incident angle can bereceived by the light-receiving element 87. Further, it is possible torealize a small size of the dose sensor 85 in the same manner as in thesixth embodiment.

The foregoing explanation has been made as exemplified by the case inwhich the diffusion plate 86, in which the minute irregularities areformed on only one surface 86 a, is used. However, it is also preferableto use a diffusion plate 86 in which minute irregularities are formed onboth surfaces (86 a, 86 b). Alternatively, a diffraction plate, in whichDOE (diffractive optical element) is formed for allowing the incomingexposure beam to come into the light-receiving element while diffractingthe exposure beam in accordance with the diffractive function, may beused in place of the diffusion plate 86. In this case, it is desirablethat DOE is designed so that the angle of diffraction is small for thelight flux having a large incident angle, and the diffraction isincreased for the light flux having a large incident angle. When thediffraction plate is used, those appropriately usable include one inwhich DOE is formed on only one surface and one in which DOE is formedon both surfaces. The diffusion plate and the diffraction plate asdescribed above can be also applied to the irradiation irregularitysensor.

Eighth Embodiment

Next, an exposure apparatus according to an eighth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1. However, thestructure of the exposure beam sensor 27 differs. The exposure beamsensor 27 provided for the exposure apparatus of this embodimentperforms the measuring operation through the liquid LQ on the imageplane side of the projection optical system PL, in the same manner as inthe second to fifth embodiments described above. However, thisembodiment will be principally explained about a dose sensor providedfor the exposure beam sensor 27.

FIG. 14 shows a schematic arrangement of the dose sensor provided forthe exposure apparatus according to the eighth embodiment of the presentinvention. As shown in FIG. 14, the dose sensor 90 provided for theexposure apparatus of this embodiment is constructed to include afluorescent plate 91 and a light-receiving element 92. The fluorescentplate 91 is provided in the opening 32 formed for the chassis 30 whileallowing the upper surface to make coincidence. The fluorescent plate 91is excited by the incoming exposure beam to emit the fluorescence or thephosphorescence having a wavelength different from that of the exposurebeam. In other words, the fluorescent plate 91 effects the wavelengthconversion, for example, into the light in the visible region for theexposure beam having the wavelength in the vacuum ultraviolet region.Those usable as the fluorescent plate 91 include, for example, alight-transmissive plate which contains an organic dye material and alight-transmissive plate which has the surface coated with an organicdye for absorbing the exposure beam to emit the fluorescence or thephosphorescence having the wavelength longer than that of the exposurebeam. In this arrangement, the light-receiving element can beappropriately selected depending on the sensitivity of the fluorescencewavelength.

A waterproof countermeasure is applied with a seal member or the likebetween the fluorescent plate 91 and the chassis 30. The light-receivingelement 92 has such a characteristic that the light, which is in thewavelength region (for example, visible region) different from thewavelength of the exposure beam, is received. The light-receivingelement 92 is arranged at the position closely to the fluorescent plate91, while an approximately central portion of the light-receivingsurface 92 a is positioned just under an approximately central portionor the center of the fluorescent plate 91 (in the −Z direction). An ARcoat for the light in the visible region including the fluorescence andthe phosphorescence is applied to the light-receiving surface 92 a ofthe light-receiving element 92.

When the light amount of the exposure beam radiated onto the exposurearea is measured by using the dose sensor 90 of this embodiment, themeasurement is performed in such a state that the illumination conditionof the illumination optical system IS is set to the illuminationcondition to be established when the exposure process is performed forthe wafer W, and the liquid LQ is supplied to the space between theprojection optical system PL and the upper surface 33 of the chassis 30,in the same manner as in the sixth and seventh embodiments. Therelationship between the amount of the light come into the fluorescentplate 91 and the amount of the light subjected to the wavelengthconversion and outgone from the fluorescent plate 91 is previouslydetermined before measuring the light amount of the exposure beam.

When the exposure beam comes into the projection optical system PL inthe state in which the illumination condition of the illuminationoptical system IS is set to the illumination condition during theexposure, the exposure beam passes through the projection optical systemPL without being totally reflected at the end portion of the projectionoptical system PL, and the exposure beam comes into the fluorescentplate 91 through the liquid LQ. When the exposure beam comes into thefluorescent plate 91, a part or all of the light amount thereof isabsorbed by the fluorescent plate 91 to emit the fluorescence or thephosphorescence having the light amount corresponding to the absorbedlight amount. The fluorescence or the phosphorescence has the wavelengthwhich is different from the wavelength of the exposure beam, whichoutgoes from the fluorescent plate 91 in directions not depending on theincident angle of the exposure beam. After that, the fluorescence or thephosphorescence has come into the light-receiving surface 92 a of thelight-receiving element 92 and received.

As described above, also in this embodiment, the exposure beam, whichcomes into the liquid LQ from the projection optical system PL, does notpass through the gas until the exposure beam outgoes from thefluorescent plate 91. Therefore, even when the exposure beam having alarge incident angle comes into the fluorescent plate 91, the exposurebeam is not totally reflected. Further, even when the exposure beamhaving the large incident angle comes, the exposure beam is convertedinto the fluorescence or the phosphorescence having the differentwavelength to outgo in the directions different from the incident angleas well. Therefore, the light beam is easily received by thelight-receiving element 92. Further, it is possible to realize a smallsize of the dose sensor 90 in the same manner as in the sixth andseventh embodiments.

When all of the exposure beam come into the fluorescent plate 91 is notconverted into the fluorescence or the phosphorescence having thedifferent wavelength, a part of the exposure beam passes through thefluorescent plate 91 to come into the light-receiving element 92. Asdescribed above, the light-receiving characteristic of thelight-receiving element 92 is such a characteristic that the light beamin the wavelength region different from that of the exposure beam isreceived. Therefore, no serious problem arises even when the exposurebeam comes into the light-receiving element 92. However, when anymeasurement error arises, for example, due to the generation of heat onaccount of the fact that the exposure beam transmitted through thefluorescent plate 91 comes into the light-receiving element 92, it ispreferable to provide, between the fluorescent plate 91 and thelight-receiving element 92, a filter through which the light beam in thewavelength region including the fluorescence or the phosphorescencegenerated by the fluorescent plate 91 is transmitted and which blocks orshields the light beam in the wavelength region including the exposurebeam.

Ninth Embodiment

Next, an exposure apparatus according to a ninth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1. However, thestructure of the exposure beam sensor 27 differs. The exposure beamsensor 27 provided for the exposure apparatus of this embodimentperforms the measuring operation through the liquid LQ on the imageplane side of the projection optical system PL, in the same manner as inthe second to fifth embodiments described above. An explanation will bemade principally about an irradiation irregularity sensor provided forthe exposure beam sensor 27. It is a matter of course that thisembodiment is also applicable to the dose sensor described above and thespatial image-measuring unit as described later on.

FIG. 15 shows a schematic arrangement of the irradiation irregularitysensor provided for the exposure apparatus according to the ninthembodiment of the present invention. As shown in FIG. 15A, theirradiation irregularity sensor 100 provided for the exposure apparatusof this embodiment is constructed to include a waveguide member 101 anda light-receiving element 102. The waveguide member 101 has a columnarshape having a diameter larger than the diameter of the pinhole 31formed for the chassis 30 shown in FIG. 3. The waveguide member 101 isarranged in a state in which one end 101 a abuts against the lowerportion of the pinhole 31 (in the −Z direction), while allowing thecentral axis to be approximately coincident with the central position ofthe pinhole 31.

The waveguide member 101 is composed of synthetic quartz or fluorite.The exposure beam, which comes from one end 101 a into the inside,undergoes the waveguide while effecting the total reflection at theouter circumference (boundary between the air and the waveguide member)to allow the exposure beam to outgo from the other end 101 b. Thoseusable as the waveguide member 101 include, for example, an opticalfiber and a rod integrator as a type of optical integrator. A waterproofcountermeasure is applied by a seal member or the like for the portionof the waveguide member 101 which abuts against the chassis 30. Thelight-receiving element 102 has such a characteristic that the light inthe wavelength region including the exposure beam is received. Thelight-receiving element 102 is arranged in a state in which thelight-receiving surface 102 a abuts against the other end 101 b of thewaveguide member 101. An AR coat for the ArF laser beam is applied tothe light-receiving surface 102 a of the light-receiving element 102.

The reason, why the light-receiving surface 102 a of the light-receivingelement 102 is in contact with the other end 101 b of the waveguidemember 101, is that the exposure beam having a large outgoing angle,which has outgone from the other end 101 b, has come into thelight-receiving surface 102 a of the light-receiving element 102 andreceived. In other words, the following reason is affirmed. That is, theexposure beams having various angles outgo from the other end 101 b ofthe waveguide member 101. Therefore, all of the exposure beams, whichhave outgo while making expansion, cannot be allowed to come into thelight-receiving surface 102 a, and especially it is impossible toreceive the exposure beam having the large outgoing angle in a state inwhich the other end 101 b of the waveguide member 101 is separated fromthe light-receiving surface 102 a of the light-receiving element 102.

When the light amount of the exposure beam radiated onto the exposurearea is measured by using the irradiation irregularity sensor 100 ofthis embodiment, the measurement is performed in such a state that theillumination condition of the illumination optical system IS is set tothe illumination condition to be established when the exposure processis performed for the wafer W, and the liquid LQ is supplied to the spacebetween the projection optical system PL and the upper surface 33 of thechassis 30, in the same manner as in the sixth to eighth embodiments.When the exposure beam comes into the projection optical system PL inthis state, then the exposure beam is not totally reflected at the endportion of the projection optical system PL, and the exposure beampasses through the projection optical system PL. The exposure beam comesinto the waveguide member 101 from one end 101 a through the liquid LQand the pinhole 31. The exposure beam, which has come into the waveguidemember 101, advances in the waveguide member 101 while being reflectedby the outer circumference of the waveguide member 101. The exposurebeam is received by the light-receiving element 102 arranged in thestate of abutment against the other end 101 b of the waveguide member101.

As described above, in this embodiment, the exposure beam, which comesinto the liquid LQ from the projection optical system PL and whichpasses through the pinhole 31, comes into the waveguide member 101without passing through the gas. Therefore, it is possible to receive agreater part of the exposure beam radiated onto the exposure areaincluding the exposure beam having the large incident angle. Theforegoing explanation has been made about the case in which the exposurebeam is subjected to the waveguide while effecting the total reflectionat the outer circumference by utilizing the difference in the refractiveindex between the waveguide member 101 and the air. However, when theincident angle of the exposure beam with respect to the outercircumference is small, the exposure beam sometimes outgo from the outercircumference to the outside. Therefore, it is desirable that a metalsuch as Cr (chromium) is vapor-deposited on the outer circumference ofthe waveguide member 101.

In view of the structure of the irradiation irregularity sensor 100, itis also assumed that the waveguide member 101 and the light-receivingmember 102 are inevitably arranged separately. In such a situation, asshown in FIG. 15B, it is desirable that the shape of the other end 101 bis a curved shape (lens shape) to maximally decrease the outgoing angleof the exposure beam allowed to advance in the waveguide member 101.Further, the foregoing embodiment has been explained about the columnarwaveguide member 101. However, those usable for the shape thereofinclude quadratic prism shapes and other shapes.

Tenth Embodiment

Next, an exposure apparatus according to a tenth embodiment of thepresent invention will be explained. The entire structure of theexposure apparatus of this embodiment is constructed in approximatelythe same manner as the exposure apparatus shown in FIG. 1. However, thestructure of the exposure beam sensor 27 differs. The exposure beamsensor 27 provided for the exposure apparatus of this embodimentperforms the measuring operation through the liquid LQ on the imageplane side of the projection optical system PL, in the same manner as inthe second to fifth embodiments described above. An explanation will bemade principally about an irradiation irregularity sensor provided forthe exposure beam sensor 27.

FIG. 16 shows a schematic arrangement of the irradiation irregularitysensor provided for the exposure apparatus according to the tenthembodiment of the present invention. As shown in FIG. 16, theirradiation irregularity sensor 110 provided for the exposure apparatusof this embodiment is constructed to include an integrating sphere 111as a type of optical integrator and a light-receiving element 112. Theintegrating sphere 111 is composed of synthetic quartz or fluorite.Parts of the integrating sphere 111 are cut out to be flat to form anincoming section 111 a and an outgoing section 111 b.

The incoming section 111 a has a diameter which is set to be larger thanthe diameter of the pinhole 31 formed for the chassis 30 shown in FIG.3. The integrating sphere 111 is arranged under the pinhole 31 (in the−Z direction) in a state in which the central position of the incomingsection 111 a is approximately coincident with the central position ofthe pinhole 31, and the circumference of the pinhole 31 is in contactwith the outer circumference of the incoming section 111 a. A waterproofcountermeasure is applied with a seal member or the like for the portionat which the incoming section 111 a abuts against the chassis 30.

The outgoing section 111 b is formed to have the diameter of apredetermined size at a predetermined position with respect to theincoming section 111 a. The position, at which the outgoing section 111b is formed, is, for example, a position of crossing at the right anglebetween a straight line which passes through the center of the incomingsection 111 a and which is perpendicular to the incoming section 111 aand a straight line which passes through the center of the outgoingsection 111 b and which is perpendicular to the outgoing section 111 b.In the example shown in FIG. 16, the outgoing section 111 b is providedwith a guide section 111 c for reflecting the exposure beam having alarge outgoing angle to introduce the exposure beam into thelight-receiving element 112.

The light-receiving element 112 has such a characteristic that the lightin the wavelength region including the exposure beam is received. Thelight-receiving element 112 is arranged in a state in which thelight-receiving surface 112 a is directed toward the outgoing section111 b. An AR coat for the ArF laser beam is applied to thelight-receiving surface 112 a of the light-receiving element 112. Inthis case, an explanation will be made about the arrangement in whichthe guide section 111 c is provided for the outgoing section 111 b ofthe integrating sphere 111 to arrange the integrating sphere 111 and thelight-receiving element 112 separately. However, another arrangement isalso available, in which the guide section 111 c is omitted, and thelight-receiving surface 112 a of the light-receiving element 112 is incontact with the outgoing section 111 b of the integrating sphere 111.

When the light amount of the exposure beam radiated onto the exposurearea is measured by using the irradiation irregularity sensor 110 ofthis embodiment, the measurement is performed in such a state that theillumination condition of the illumination optical system IS is set tothe illumination condition to be established when the exposure processis performed for the wafer W, and the liquid LQ is supplied to the spacebetween the projection optical system PL and the upper surface 33 of thechassis 30, in the same manner as in the sixth to ninth embodiments.When the exposure beam comes into the projection optical system PL inthis state, then the exposure beam is not totally reflected at the endportion of the projection optical system PL, and the exposure beampasses through the projection optical system PL. The exposure beam comesinto the integrating sphere 111 from the light-incoming end 111 athrough the liquid LQ and the pinhole 31 without passing through thegas. The exposure beam, which has come into the integrating sphere 111,is multiply reflected by the outer circumference of the integratingsphere 111. Finally, the exposure beam outgoes from the light-outgoingend 111 b. The light beam, which is included in the exposure beamoutgone from the light-outgoing end 111 b and which has a small outgoingangle, directly comes into the light-receiving surface 112 a. The lightbeam, which has a large outgoing angle, is reflected by the guidesection 111 c, and then the light beam is allowed to come into thelight-receiving surface 112 and received.

As described above, also in this embodiment, the exposure beam, whichcomes into the liquid LQ from the projection optical system PL and whichpasses through the pinhole 31, comes into the integrating sphere 111without passing through the gas. Therefore, even when the exposure beamhaving a large incident angle comes into the light-incoming end 111 a,then the exposure beam is not totally reflected, and the exposure beamcan be finally received by the light-receiving element 112. It isdesirable that a metal such as Cr (chromium) is vapor-deposited on theentire integrating sphere 111 except for the incoming section 111 a andthe outgoing section 111 b, in the same manner as in the ninthembodiment described above.

Other Embodiments

The second to fifth embodiments have been explained as exemplified bythe case in which one plano-convex lens 41, 45, 52, 57, 62, 71 isprovided as the light-collecting member for collecting the exposurebeam. The sixth to tenth embodiments have been explained about thearrangement in which the light-collecting plate 81, the diffusion plate86, the fluorescent plate 91, the waveguide member 101, or theintegrating sphere 111 is included as the optical system for allowingthe exposure beam to come into the light-receiving element. However, itis desirable to adopt an arrangement in which a plurality of lenses areprovided between the plano-convex lens 41, 45, 52, 57, 62, 71 and thelight-receiving element as well as between the light-collecting plate81, the diffusion plate 86, the fluorescent plate 91, the waveguidemember 101, or the integrating sphere 111 and the light-receivingelement to introduce the exposure beam or the like into thelight-receiving element.

FIG. 17 shows a modified embodiment of the irradiation irregularitysensor 40 provided for the exposure apparatus according to the secondembodiment. In the example shown in FIG. 17, two lenses 121, 122 areprovided between the plano-convex lens 41 and the light-receivingelement 42 in order that the exposure beam from the plano-convex lens41, especially the exposure beam having the large incident angle isconverted into the parallel light beam more easily. The exposure beam,which is converted into the parallel light beam by providing the lenses121, 122 between the plano-convex lens 41 and the light-receivingelement 42, is introduced into the light-receiving element 42. Thelenses as described above can be also used for the third to tenthembodiments. The number of the lens or lenses may be arbitrary.

The second to tenth embodiments have been explained as exemplified bythe case in which the illumination condition of the illumination opticalsystem IS is set to the illumination condition to be established whenthe exposure process is performed for the wafer W, and the unevenilluminance is measured in the state in which the liquid LQ is suppliedto the image plane side of the projection optical system PL. However,also in these embodiments, the angular aperture of the exposure beam canbe adjusted to measure, for example, the unevenness and the light amountby adjusting the light flux distribution of the exposure beam at theoutgoing plane CJ by arranging the aperture diaphragm 8 e having theminute σ value at the outgoing plane CJ of the second fly's eye lens 7in the state in which the liquid LQ is not supplied to the image planeside of the projection optical system PL, in the same manner as in thefirst embodiment.

In the exposure apparatus shown in FIG. 1, the irradiation irregularitysensor and the dose sensor are provided in one chassis 30. However, theirradiation irregularity sensor and the dose sensor may be separately onthe wafer stage 15. When the surface (upper surface) of the exposurebeam sensor 27 to make contact with the liquid is water-repellent inorder to recover the liquid LQ with ease, it is feared that the waterrepellence may be deteriorated by the radiation of the exposure beam(ultraviolet radiation). Therefore, when the measurement is performed byusing the sensor having the water-repellent surface to make contact withthe liquid LQ, an energy (light amount) adjuster provided with aplurality of ND filters, which is disclosed, for example, in JapanesePatent Application Laid-open No. 2001-144044 (corresponding to U.S. Pat.No. 6,730,925), may be appropriately used to attenuate the light amountof the exposure beam to not more than 50% and desirably not more than20% of the maximum light amount.

In the embodiments described above, the explanation has been made aboutthe irradiation irregularity sensor for measuring the uneven illuminanceand the totalized uneven light amount and the dose sensor for measuringthe light amount (radiation amount) of the exposure beam radiated ontothe image plane side of the projection optical system PL. However, thepresent invention is also applicable, for example, to a sensor whichmeasures the wavefront aberration as disclosed in U.S. Pat. No.6,650,399, a spatial image-measuring sensor which measures, for example,the imaging characteristic as disclosed in Japanese Patent ApplicationLaid-open No. 2002-14005 (corresponding to United State PatentPublication No. 2002/0041377), and a sensor which is detachable withrespect to a substrate stage as disclosed in Japanese Patent ApplicationLaid-open No. 11-238680 and International Publication No. 02/063664(corresponding to United State Patent Publication No. 2004/0090606).Even when the numerical aperture of the projection optical system islarge, the exposure beam, which has passed through the projectionoptical system, can be received. It is possible to execute various typesof measurements at desired accuracies. The disclosures of the patentdocuments are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

Eleventh Embodiment

An exposure apparatus according to an eleventh embodiment of the presentinvention will be explained below with reference to the drawings. FIG.20 shows a schematic arrangement illustrating an embodiment of theexposure apparatus of the present invention.

With reference to FIG. 20, the exposure apparatus EX comprises a maskstage MST which supports the mask M, a substrate stage PST whichsupports the substrate P, an illumination optical system IL whichilluminates, with the exposure beam EL, the mask M supported by the maskstage MST, a projection optical system PL which projects an image of thepattern of the mask M illuminated with the exposure beam EL onto thesubstrate P supported by the substrate stage PST to perform theexposure, a control unit CONT which integrally controls the overalloperation of the exposure apparatus EX, and a memory unit MRY which isconnected to the control unit CONT and which stores various types ofinformation in relation to the exposure process. The exposure apparatusEX further comprises a spatial image-measuring unit 270 which is used tomeasure the imaging characteristic (optical characteristic) of theprojection optical system PL. The spatial image-measuring unit 270 isprovided with a light receiver 290 which receives the light beam(exposure beam EL) which has passed through the projection opticalsystem PL via a slit plate 275 having a slit section 271 arranged on theimage plane side of the projection optical system PL.

The exposure apparatus EX of this embodiment is a liquid immersionexposure apparatus to which the liquid immersion method is applied inorder that the exposure wavelength is substantially shortened to improvethe resolution and the depth of focus is substantially widened. Theexposure apparatus EX comprises a liquid supply mechanism 210 whichsupplies the liquid LQ onto the substrate P, and a liquid recoverymechanism 220 which recovers the liquid LQ from the substrate P. Theexposure apparatus EX forms a liquid immersion area AR2 (locally) on apart of the substrate P including a projection area AR1 of theprojection optical system PL by the liquid LQ supplied from the liquidsupply mechanism 210 at least during the period in which the image ofthe pattern of the mask M is transferred onto the substrate P.Specifically, the exposure apparatus EX is operated as follows. That is,the space between the surface of the substrate P and the optical element260 on the side of the end portion (image plane side) of the projectionoptical system PL is filled with the liquid LQ. The image of the patternof the mask M is projected onto the substrate P to expose the substrateP therewith by irradiating the exposure beam EL via the projectionoptical system PL and the liquid LQ disposed between the projectionoptical system PL and the substrate P.

This embodiment will be explained as exemplified by a case of the use ofthe scanning type exposure apparatus (so-called scanning stepper) as theexposure apparatus EX in which the substrate P is exposed with thepattern formed on the mask M while synchronously moving the mask M andthe substrate P in mutually different directions (opposite directions)in the scanning directions. In the following explanation, the Z axisdirection resides in the direction which is coincident with the opticalaxis AX of the projection optical system PL, the X axis directionresides in the synchronous movement direction (scanning direction) forthe mask M and the substrate P in the plane perpendicular to the Z axisdirection, and the Y axis direction resides in the direction(non-scanning direction) perpendicular to the Z axis direction and the Xaxis direction. The directions of rotation (inclination) about the Xaxis, the Y axis, and the Z axis are designated as θX, θY, and θZdirections respectively. The term “substrate” referred to hereinincludes those obtained by coating a semiconductor wafer surface with aphotoresist as a photosensitive material, and the term “mask” includes areticle formed with a device pattern to be subjected to the reductionprojection onto the substrate.

The illumination optical system IL converts the light flux (laser beam)LB radiated from a light source 201 into the exposure beam EL toilluminate, with the exposure beam EL, the mask M supported by the maskstage MST. Those usable as the exposure beam EL radiated from theillumination optical system IL include, for example, emission lines(g-ray, h-ray, i-ray) in the ultraviolet region radiated, for example,from a mercury lamp, far ultraviolet light beams (DUV light beams) suchas the KrF excimer laser beam (wavelength: 248 nm), and vacuumultraviolet light beams (VUV light beams) such as the ArF excimer laserbeam (wavelength: 193 nm) and the F₂ laser beam (wavelength: 157 nm). Inthis embodiment, the ArF excimer laser beam is used.

In this embodiment, pure water is used for the liquid LQ. Those capableof being transmitted through pure water include the ArF excimer laserbeam as well as the emission line (g-ray, h-ray, i-ray) in theultraviolet region radiated, for example, from a mercury lamp and thefar ultraviolet light beam (DUV light beam) such as the KrF excimerlaser beam (wavelength: 248 nm).

In this embodiment, the light source 201 is an excimer laser lightsource for irradiating the ArF excimer laser beam (wavelength: 193 nm).The control unit CONT controls, for example, the switching ON/OFF of thelaser beam emission, the central wavelength, the spectrum half valuewidth, and the repeating frequency.

The illumination optical system IL includes, for example, a beam-shapingoptical system 202, an optical integrator 203, an illumination systemaperture diaphragm plate 204, a relay optical system 206, 208, a fixedmask blind 207A, a movable mask blind 207B, a mirror 209, and acondenser lens 230. In this embodiment, a fly's eye lens is used as theoptical integrator 203. However, it is also allowable to use, forexample, a rod type (internal reflection type) integrator or adiffraction optical element. For example, a cylindrical lens or a beamexpander is included in the beam-shaping optical system 202 in orderthat the cross-sectional shape of the laser beam LB pulse-emitted by thelight source 201 is shaped so that the laser beam LB efficiently comesinto the optical integrator 203 provided on the downstream side of theoptical path for the laser beam LB. The optical integrator (fly's eyelens) 203 is arranged on the optical path for the laser beam LB radiatedfrom the beam-shaping optical system 202 to form a surface light sourcecomposed of a large number of point light sources (light source images),i.e., a secondary light source in order to illuminate the mask M with auniform illuminance distribution.

The illumination system aperture diaphragm plate 204, which is composedof a disk-shaped member, is arranged in the vicinity of the outgoingside focal plane of the optical integrator 203. Those arranged atapproximately equal angular intervals in the illumination systemaperture diaphragm plate 204 include, for example, an aperture diaphragm(ordinary diaphragm) composed of an ordinary circular aperture, anaperture diaphragm (small σ diaphragm) composed of a small circularaperture to decrease the σ value as the coherence factor, an aperturediaphragm (zonal diaphragm) for the zonal illumination, and a modifiedaperture diaphragm composed of a plurality of apertures arrangedeccentrically for the modified light source method (four-spotillumination diaphragm referred to as “SHRINC” as well). Theillumination system aperture diaphragm plate 204 is rotated by a drivingunit 231 such as a motor controlled by the control unit CONT.Accordingly, any one of the aperture diaphragms is selectively arrangedon the optical path for the exposure beam EL.

In this embodiment, the illumination system aperture diaphragm plate 204is used to adjust the light intensity distribution on the pupil plane ofthe illumination optical system IL. However, it is also allowable to useanother optical system as disclosed in U.S. Pat. No. 6,563,567. Thedisclosure thereof is incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

A beam splitter 205, which has a small reflectance and a largetransmittance, is arranged on the optical path for the exposure beam ELwhich has passed through the illumination system aperture diaphragmplate 204. Further, the relay optical system (206, 208) is arranged onthe optical path downstream therefrom with the mask blinds 207A, 2079intervening therebetween. The fixed mask blind 207A is arranged on theplane slightly defocused from the conjugate plane with respect to thepattern surface of the mask M, for which a rectangular aperture isformed to define the illumination area IA on the mask M. The movablemask blind 207B, which has an aperture with the variable width and thevariable position in the directions corresponding to the scanningdirection (X axis direction) and the non-scanning direction (Y axisdirection) perpendicular thereto respectively, is arranged in thevicinity of the fixed mask blind 207A. The illumination area IA isrestricted by the aid of the variable mask blind 2072 upon the start andthe completion of the scanning exposure. Thus, the exposure for anyunnecessary portion is avoided. In this embodiment, the movable maskblind 207B is also used to set the illumination area when the spatialimage is measured as described later on. On the other hand, alight-collecting lens 232, and an integrator sensor 233 composed of alight-receiving element such as a PIN type photodiode havingsatisfactory sensitivity in the far ultraviolet region and having a highresponse frequency in order to detect the pulse light emission of thelight source 201 are arranged on the optical path for the exposure beamEL reflected by the beam splitter 205 included in the illuminationoptical system IL.

The function of the illumination optical system IL constructed asdescribed above will be briefly explained. The laser beam LB, which ispulse-emitted from the light source 201, comes into the beam-shapingoptical system 202, and the cross-sectional shape thereof is shapedherein to efficiently come into the optical integrator 203 on thedownstream side. After that, the laser beam LB comes into the opticalintegrator 203. Accordingly, the secondary light source is formed on theoutgoing side focal plane of the optical integrator 203 (pupil plane ofthe illumination optical system IL). The exposure beam EL, which outgoesfrom the secondary light source, passes through any one of the aperturediaphragms on the illumination system aperture diaphragm plate 204, andthen the exposure beam EL comes into the beam splitter 205 having thelarge transmittance and the small reflectance. The exposure beam EL,which is transmitted through the beam splitter 205, passes through thefirst relay lens 206, and the exposure beam EL passes through therectangular aperture of the fixed mask blind 207A and the movable maskblind 207B. After that, the exposure beam EL passes through the secondrelay lens 208, and the optical path is bent vertically downwardly bythe mirror 209. The exposure beam EL, for which the optical path hasbeen bent by the mirror 209, passes through the condenser lens 203 toilluminate, with the uniform illuminance distribution, the illuminationarea IA on the mask M retained by the mask stage MST.

On the other hand, the exposure beam EL, which is reflected by the beamsplitter 205, is received by the integrator sensor 233 via thelight-collecting lens 232. The photoelectric conversion signal of theintegrator sensor 233 is supplied to the control unit via a signalprocessing unit having an A/D converter and an unillustrated peak holdcircuit. In this embodiment, the measured value of the integrator sensor233 is used to control the exposure amount, and the measured value isalso used to calculate the radiation amount for the projection opticalsystem PL. The radiation amount is used to calculate the amount ofchange of the imaging characteristic caused by the absorption of theillumination light beam by the projection optical system PL togetherwith the substrate reflectance (this value can be also determined on thebasis of the output of the integrator sensor and the output of anunillustrated reflectance monitor). In this embodiment, the radiationamount is calculated at predetermined intervals by the control unit CONTon the basis of the output of the integrator sensor 233. The result ofthe calculation is stored as the radiation hysteresis in the memory unitMRY:

The mask stage MST is movable while retaining the mask M. The mask M isfixed, for example, by the vacuum attraction (or the electrostaticattraction). The mask stage MST is supported in a non-contact mannerover a mask base 255 by the aid of a gas bearing (air bearing) as anon-contact bearing. The mask stage MST is two dimensionally movable inthe plane perpendicular to the optical axis AX of the projection opticalsystem PL, i.e., in the XY plane and finely rotatable in the OZdirection by the mask stage-driving unit MSTD including a linear motoror the like. The mask stage MST is movable over the mask base 255 at adesignated scanning velocity in the X axis direction. The mask stage MSThas the movement stroke of such an extent that the entire surface of themask M can traverse at least the optical axis AX of the projectionoptical system PL.

A movement mirror 241 is provided on the mask stage MST. A laserinterferometer 242 is provided at the position opposed to the movementmirror 241. The position in the two-dimensional direction and the angleof rotation in the θZ direction (sometimes including the angles ofrotation in the θX direction and in the θY direction as well) of themask M on the mask stage MST are measured in real time by the laserinterferometer 242. The measurement result is outputted to the controlunit CONT. The control unit CONT controls the position of the mask Msupported by the mask stage MST by driving the mask stage-driving unitMSTD on the basis of the measurement result of the laser interferometer242.

The projection optical system PL projects the pattern of the mask M ontothe substrate P at a predetermined projection magnification β. Theprojection optical system PL comprises a plurality of optical elementsincluding an optical element (lens) 260 provided at the end portion onthe side of the substrate P. The optical elements are supported by abarrel PK. In this embodiment, the projection optical system PL residesin the reducing system in which the projection magnification β is, forexample, ¼ or ⅕. The projection optical system PL may be based on anyone of the 1× magnification system and the magnifying system. Theprojection optical system PL may be based on any one of the dioptricsystem, the catoptric system, and the cata-dioptric system.

The optical element 260, which is disposed at the end portion of theprojection optical system PL of this embodiment, is retained by a lenscell 262. The lens cell 262, which retains the optical element 260, isconnected by a connecting mechanism 261 to the end portion of the barrelPK. The liquid LQ in the liquid immersion area AR2 makes contact withthe optical element 260. The optical element 260 is formed of fluorite.The fluorite has a high affinity for water. Therefore, the liquid LQ canbe in tight contact with the substantially entire surface of the liquidcontact surface 260 a of the optical element 260. That is, in thisembodiment, the liquid (water) LQ is supplied, which has the highaffinity for the liquid contact surface 260 a of the optical element260. Therefore, the tight contact performance is enhanced between theliquid LQ and the liquid contact surface 260 a of the optical element260. It is possible to reliably fill the optical path between theoptical element 260 and the substrate P with the liquid LQ. The opticalelement 260 may be made of quartz which has a high affinity for water.Alternatively, a water-attracting (lyophilic or liquid-affinitive)treatment may be performed to the liquid contact surface 260 a of theoptical element 260 to further enhance the affinity for the liquid LQ.

The substrate stage PST is movable while retaining the substrate P. Thesubstrate stage PST is constructed to include an XY stage 253 and a Ztilt stage 252 which is provided on the XY stage 253. The XY stage 253is supported in a non-contact manner by the aid of a gas bearing (airbearing) as an unillustrated non-contact bearing over the upper surfaceof a stage base 254. The XY stage 253 is two dimensionally movable inthe plane perpendicular to the optical axis AX of the projection opticalsystem PL, i.e., in the XY plane and finely rotatable in the θZdirection by the substrate stage-driving unit PSTD including a linearmotor or the like. The Z tilt stage is provided on the XY stage 253. Asubstrate holder 251 is provided on the Z tilt stage 252. The substrateP is retained, for example, by the vacuum attraction by the substrateholder 251. The Z tilt stage 252 is provided movably in the Z axisdirection, the θX direction, and the θY direction as well by an actuatoras described later on. The substrate stage-driving unit PSTD, whichincludes the actuator, is controlled by the control unit CONT. Thesubstrate stage PST controls the focus position (Z position) and theangle of inclination of the substrate P so that the surface of thesubstrate P is adjusted to match the image plane of the projectionoptical system PL in the auto-focus manner and the auto-leveling manner.Further, the substrate stage PST positions the substrate P in the X axisdirection and the Y axis direction.

An auxiliary plate 257 is provided on the substrate stage PST (substrateholder 251) so that the substrate P is surrounded thereby. The auxiliaryplate 257 has a flat surface having approximately the same height asthat of the surface of the substrate P retained by the substrate holder251. Even when the edge area of the substrate P is subjected to theexposure, the liquid LQ can be retained under the projection opticalsystem PL owing to the auxiliary plate 257.

The auxiliary plate 257 is formed only around the substrate holder 251.However, the auxiliary plate 257 can be also arranged around the spatialimage-measuring unit 270 and between the substrate holder 251 and thespatial image-measuring unit 270 so that the upper surface of thesubstrate stage PST is substantially flush. Accordingly, even when theupper surface of the spatial image-measuring unit 270 is smaller thanthe liquid immersion area AR2, the liquid LQ can be retained under theprojection optical system PL owing to the auxiliary plate 257.

A movement mirror 243 is provided on the substrate stage PST (Z tiltstage 252). A laser interferometer 244 is provided at the positionopposed to the movement mirror 243. The two-dimensional direction andthe angle of rotation of the substrate P on the substrate stage PST aremeasured in real time by the laser interferometer 244. The measurementresult is outputted to the control unit CONT. The control unit CONTpositions the substrate P supported by the substrate stage PST bydriving the substrate stage-driving unit PSTN including, for example,the linear motor on the basis of the measurement result of the laserinterferometer 244.

The exposure apparatus EX further comprises a focus-detecting system 245which detects the position of the surface of the substrate P supportedby the substrate stage PST (substrate holder 251). The focus-detectingsystem 245 includes a light-emitting section 245A which emits thedetecting light flux in an oblique direction through the liquid LQ ontothe substrate P, and a light receiver 245B which receives the reflectedlight beam of the detecting light flux reflected by the substrate P. Thelight-receiving result of the focus-detecting system 245 (light receiver245B) is outputted to the control unit CONT. The control unit CONT candetect the position information in the Z axis direction about thesurface of the substrate P on the basis of the detection result of thefocus-detecting system 245. The information about the inclination of thesubstrate P in the θX and θY directions can be detected by emitting aplurality of detecting light fluxes from the light-emitting section245A. The structure usable for the focus-detecting system 245 isdisclosed, for example, in Japanese Patent Application Laid-open No.6-283403 (corresponding to U.S. Pat. No. 5,448,332). The disclosurethereof is incorporated herein by reference within a range of permissionof the domestic laws and ordinances of the state designated or selectedin this international application. Another system is also usable as thefocus-detecting system 245, in which the detecting light flux is emittedonto the surface of the substrate P without passing through the liquidLQ outside the liquid immersion area AR2 to receive the reflected lightbeam thereof.

The control unit CONT controls the movement in the Z axis direction andthe two-dimensional inclination (rotation in the θX and θY directions)of the Z tilt stage 252 by the aid of the substrate stage-driving unitPSTD including Z position-driving sections 256A to 256C (see, forexample, FIG. 21) as described later on so that the focal deviation iszero on the basis of the focal deviation signal (defocus signal), forexample, the S-curve signal supplied from the light receiver 245B, forexample, during the scanning exposure. That is, the control unit CONTexecutes the autofocus and the autoleveling to substantially match theimaging plane of the projection optical system PL and the surface of thesubstrate P by controlling the movement of the Z tilt stage 252 by usingthe multiple-point focus-detecting system 245.

A substrate alignment system 246 based on the off-axis system, whichdetects an alignment mark formed on the substrate P or a reference markformed on an unillustrated reference member provided on the substratestage PST, is provided in the vicinity of the end portion of theprojection optical system PL. A mask alignment system 247, which detectsthe reference mark provided on the reference member via the mask M andthe projection optical system PL, is provided in the vicinity of themask stage MST. In this embodiment, an alignment sensor based on theimage processing system, i.e., the so-called FIA (Field Image Alignment)system is used as the alignment system. A system disclosed, for example,in Japanese Patent Application Laid-open No. 4-65603 (corresponding toU.S. Pat. No. 5,493,403) can be used for the substrate alignment system246. A system disclosed, for example, in Japanese Patent ApplicationLaid-open No. 7-176468 (corresponding to U.S. Pat. No. 5,646,313) can beused for the mask alignment system 247.

FIG. 21 shows a magnified view illustrating the liquid supply mechanism210, the liquid recovery mechanism 220, and the projection opticalsystem PL. The projection optical system PL comprises a plurality of(ten in this embodiment) optical elements 264 a to 264 j retained by thebarrel PK, and the optical element 260 retained by the lens cell 262 onthe image plane side of the projection optical system PL (on the side ofthe substrate P). Parts of the optical elements 264 a to 264 j forconstructing the projection optical system PL, for example, the opticalelements 264 a, 264 b are constructed to be finely drivable in thedirection of the optical axis AX and in the direction of inclinationwith respect to the XY plane by a plurality of driving elements (forexample, piezoelectric elements) 263 respectively. First and secondtightly closed chambers 265A, 265B, which are in a tightly closed staterespectively, are formed between the optical elements 264 d, 264 e andbetween the optical elements 264 f, 264 g. A clean gas, for example, dryair is supplied to the first and second tightly closed chambers 265A,265B via a pressure-adjusting mechanism 266 from an unillustrated gassupply mechanism.

In this embodiment, the pressure-adjusting mechanism 266, which adjuststhe driving voltage applied to each of the driving elements 263 (drivingamount of the driving element) and the gas pressure (internal pressure)in each of the first and second tightly closed chambers 265A, 2653, iscontrolled by an imaging characteristic control unit 267 in response tothe instruction from the control unit CONT. Accordingly, the imagingcharacteristic including, for example, the field curvature, thedistortion, and the magnification of the projection optical system PL iscorrected. The imaging characteristic-adjusting mechanism, which adjuststhe imaging characteristic as described above, may be constructed byonly the movable optical element such as the optical element 264 a. Thenumber of the movable optical element or optical elements is arbitraryas well. However, in this arrangement, the number of the movable opticalelements corresponds to the correctable types of the imagingcharacteristics of the projection optical system PL except for thefocus. Therefore, the number of the movable optical elements may bedetermined depending on the types of the imaging characteristics forwhich any correction is required.

The Z tilt stage 252 is supported at three points on the XY stage 253 bythree Z position-driving sections 256A, 256B, 256C (although the Zposition-driving section 256C on the back side of the paper surface isnot shown). The Z position-driving sections 256A to 256C are constructedto include three actuators (for example, voice coil motors) 259A, 259B,259C (although the actuator 259C on the back side of the paper surfacein FIG. 21 is not shown) which independently drive the respectivesupport points on the lower surface of the Z tilt stage 252 in thedirection of the optical axis of the projection optical system PL (inthe Z direction), and encoders 258A, 258B, 2580 (although the encoder258C on the back side of the paper surface in FIG. 21 is not shown)which detect the driving amounts in the Z axis direction (displacementfrom the reference position) provided by the Z position-driving sections256A, 256B, 256C of the Z tilt stage 252. A linear encoder, which isbased on, for example, the optical system or the capacitance system, isused for each of the encoders 258A to 258C. In this embodiment, thedriving unit, which drives the Z tilt stage 252 in the direction of theoptical axis AX (in the Z axis direction) and the directions ofinclination with respect to the surface (XY surface) perpendicular tothe optical axis, i.e., the θX and θY directions, is constructed by theactuators 256A, 256B, 256C. The driving amounts in the Z axis directionof the respective support points (displacement amounts from thereference point), which are provided by the Z position-driving sections256A, 256B, 256C of the Z tilt stage 252 and measured by the encoders258A to 258C, are outputted to the control unit CONT. The control unitCONT determines the position in the Z axis direction and the levelingamount (θX rotation amount, θY rotation amount) of the Z tilt stage 252on the basis of the measurement results of the encoders 258A to 258C.

The liquid supply mechanism 210 supplies the liquid LQ to the spacebetween the projection optical system PL and the substrate P during thepredetermined period including the period in which the exposure processis performed. The liquid supply mechanism 210 comprises a liquid supplysection 211 which is capable of feeding the liquid LQ, and supplynozzles 213 which are connected to the liquid supply section 211 via asupply tube 212 and which supply, onto the substrate P, the liquid LQfed from the liquid supply section 211. The supply nozzles 213 arearranged closely to the surface of the substrate P. The liquid supplysection 211 includes, for example, a tank for accommodating the liquidLQ, and a pressurizing pump. The liquid supply section 211 supplies theliquid LQ onto the substrate P via the supply tube 212 and the supplynozzles 213. The operation of the liquid supply section 211 forsupplying the liquid is controlled by the control unit CONT. The controlunit CONT is capable of controlling the liquid supply amount per unittime to be supplied onto the substrate P by the liquid supply section211. It is not necessarily indispensable that the exposure apparatus EXis provided with the tank, the pressurizing pump, and other componentsof the liquid supply mechanism 210. At least a part thereof can bereplaced with the equipment of the factory or the like in which theexposure apparatus EX is installed.

The liquid recovery mechanism 220 recovers the liquid LQ from the spacebetween the projection optical system PL and the substrate P in thepredetermined period including the period in which the exposure processis performed. The liquid recovery mechanism 220 comprises recoverynozzles 223 which are arranged closely to the surface of the substrateP, and a liquid recovery section 221 which is connected to the recoverynozzles 223 via a recovery tube 222. The liquid recovery section 221 isconstructed to include, for example, a vacuum system (suction unit)including a vacuum pump, and a tank for accommodating the recoveredliquid LQ. The operation of the liquid recovery section 221 iscontrolled by the control unit CONT. When the vacuum system of theliquid recovery section 221 is driven, the liquid LQ on the substrate Pis recovered by the aid of the recovery nozzles 223. As for the vacuumsystem, it is also allowable to use a vacuum system of the factory inwhich the exposure apparatus EX is arranged, without providing thevacuum pump for the exposure apparatus. Further, it is not necessarilyindispensable that the exposure apparatus EX is provided with the tankof the liquid recovery mechanism 220 as well. At least a part thereofcan be replaced with the equipment of the factory or the like in whichthe exposure apparatus EX is installed.

It is preferable that a gas/liquid separator, which separates the gasfrom the liquid LQ sucked from the recovery nozzles 223, is provided atan intermediate position of the recovery tube 222, specifically betweenthe recovery nozzles 223 and the vacuum system. When the liquid LQ onthe substrate P is sucked and recovered, there is such a possibilitythat a situation arises for the liquid recovery section (vacuum system)221 in which the liquid LQ is recovered together with the surroundinggas (air). Therefore, when the gas/liquid separator is used to separatethe gas from the liquid recovered by the recovery nozzles 223, it ispossible to avoid the occurrence of the inconvenience which would beotherwise caused, for example, such that the liquid LQ flows into thevacuum system and the vacuum system is out of order. The liquid LQrecovered by the liquid recovery section 221 is, for example, discardedor cleaned, and the liquid LQ is returned, for example, to the liquidsupply section 211 and reused.

The liquid supply mechanism 210 and the liquid recovery mechanism 220are supported separately from the projection optical system PL.Accordingly, the vibration, which is generated by the liquid supplymechanism 210 and the liquid recovery mechanism 220, is not transmittedto the projection optical system PL.

FIG. 22 shows a plan view illustrating the positional relationshipbetween the projection area AR1 of the projection optical system PL andthe liquid supply mechanism 210 and the liquid recovery mechanism 220.The projection area AR1 of the projection optical system PL has arectangular shape (slit shape) which is long in the Y axis direction.The three supply nozzles 213A to 213C are arranged on the +X side, andthe two recovery nozzles 223A, 223B are arranged on the −X side so thatthe projection area AR1 is interposed in the X axis direction. Thesupply nozzles 213A to 213C are connected to the liquid supply section211 via the supply tube 212. The recovery nozzles 223A, 223B areconnected to the liquid recovery section 221 via the recovery tube 222.The supply nozzles 216A to 216C and the recovery nozzles 226A, 226B arearranged in such a positional relationship that the supply nozzles 213Ato 213C and the recovery nozzles 223A, 223B are rotated by approximately180°. The supply nozzles 213A to 2130 and the recovery nozzles 226A,226B are arranged alternately in the Y axis direction, and the supplynozzles 216A to 216C and the recovery nozzles 223A, 223B are arrangedalternately in the Y axis direction. The supply nozzles 216A to 2160 areconnected to the liquid supply section 211 via the supply tube 215, andthe recovery nozzles 226A, 2263 are connected to the liquid recoverysection 221 via the recovery tube 225.

FIG. 23 shows a schematic arrangement illustrating the spatialimage-measuring unit 270 to be used for the measurement of the imagingcharacteristic (optical characteristic) of the projection optical systemPL. The spatial image-measuring unit 270 is provided with a lightreceiver 290 which receives the light beam which has passed through theprojection optical system PL via a slit plate 275 having a slit section271 arranged on the image plane side of the projection optical systemPL. The slit plate 275 is provided for the Z tilt stage 252 on the imageplane side of the projection optical system PL. The light receiver 290includes an optical element 276 which is arranged at a position near tothe slit plate 275 in the Z tilt stage 252, a bending mirror 277 whichbends the optical path for the light beam which has passed through theoptical element 276, an optical element 278 into which the light beamwhich has passed along the mirror 277 comes, a light-feeding lens 279which feeds the light beam which has passed through the optical element278 to the outside of the Z tilt stage 252, a mirror 280 which isprovided outside the Z tilt stage 252 and which bends the optical pathfor the light beam fed from the light-feeding lens 279, alight-receiving lens 281 which receives the light beam which has passedalong the mirror 280, and an optical sensor (light-receiving element)282 which is composed of a photoelectric conversion element forreceiving the light beam which has passed through the light-receivinglens 281.

The slit plate 275 includes a glass plate member 274 which isrectangular as viewed in a plan view, a light-shielding film 272 whichis composed of chromium or the like provided at a central portion of theupper surface of the glass plate member 274, a reflective film 273 whichis composed of aluminum or the like provided around the light-shieldingfilm 272, i.e., at portions of the upper surface of the glass platemember 274 except for the light-shielding film 272, and the slit section271 which is an aperture pattern formed at a part of the light-shieldingfilm 272. The glass plate member 274, which is a transparent member, isexposed at the slit section 271. The light beam is transmissive throughthe slit section 271.

A projection 283 is provided at a position adjacent to the substrateholder 251 on the upper surface of the Z tilt stage 252. An opening 284is provided at the upper portion of the projection 283. The slit plate275 is detachable with respect to the opening 284. The slit plate 275 isfitted vertically from an upper position in a state in which the opening284 is closed thereby.

Those usable as the material for forming the glass plate member 274include, for example, synthetic quartz and fluorite having thesatisfactory transmittance with respect to the ArF excimer laser lightbeam and the KrF excimer laser light beam. The synthetic quartz has arefractive index of 1.56 with respect to the ArF excimer laser lightbeam and a refractive index of about 1.51 with respect to the KrFexcimer laser light beam.

The optical element 276 is arranged under the slit section 271 in the Ztilt stage 252, which is retained by a holding member 285. The holdingmember 285, which retains the optical element 275, is attached to theinner wall surface 283A of the projection 283. The light beam, which haspassed through the optical element 276 arranged in the Z tilt stage 252,is subjected to the bending of the optical path thereof by the mirror277, and then the light beam passes through the optical element 278. Thelight beam, which has passed through the optical element 278, is fed tothe outside of the Z tilt stage 252 by the light-feeding lens 279 fixedto the side wall on the +X side of the Z tilt stage 252. The light beam,which has been fed to the outside of the Z tilt stage 252 by thelight-feeding lens 279, is introduced into the light-receiving lens 281by the mirror 280. The light-receiving lens 281 and the optical sensor282 arranged over the light-receiving lens 281 are accommodated in acase 286 while marinating the predetermined positional relationship. Thecase 286 is fixed to the portion in the vicinity of the upper end of asupport column 288 provided on the upper surface of the stage base 254by the aid of an attachment member 287.

For example, the mirror 277, the optical element 278, and thelight-feeding lens 279 are detachable with respect to the Z tilt stage252. The support column 288, which supports the case 286 foraccommodating the light-receiving lens 281 and the optical sensor 282,is detachable with respect to the stage base 254.

A photoelectric conversion element (light-receiving element), forexample, a photomultiplier tube (PMT), which is capable of accuratelydetecting the faint or weak light beam, is used for the optical sensor282. The photoelectric conversion signal from the optical sensor 282 isfed to the control unit CONT via a signal processing unit.

FIG. 24 shows a state in which the imaging characteristic of theprojection optical system PL is measured by using the spatialimage-measuring unit 270. As shown in FIG. 24, the liquid LQ is allowedto flow to the space between the slit plate 275 and the optical element260 on the end portion side (image plane side) of the projection opticalsystem PL by using the liquid supply mechanism 210 and the liquidrecovery mechanism 220 in a state in which the projection optical systemPL and the slit plate 275 are opposed to one another during themeasurement of the imaging characteristic of the projection opticalsystem PL. The light beam (exposure beam EL), which has passed throughthe projection optical system PL and the liquid LQ, is radiated onto theslit plate 275 for constructing the spatial image-measuring unit 270 ina state in which the space between the slit plate 275 and the opticalelement 260 of the projection optical system AL is filled with theliquid LQ. In this situation, the information about the surface positionof the upper surface 275A of the slit plate 275 can be detected by usingthe focus-detecting system 245.

FIG. 25 shows a magnified sectional view illustrating major parts of thespatial image-measuring unit 270 disposed in the vicinity of the opticalelement 276 and the slit plate 275 arranged in the projection 283. FIG.26 shows a plan view illustrating the slit plate 275 as viewed from anupper position. In FIG. 25, the light receiver 290 is depicted in asimplified manner. FIG. 25 shows only the optical sensor 282 whichreceives the light beam which has passed through the optical element 276and the optical element 276 which is arranged at the position nearest tothe slit plate 275 on the optical path for the light beam, of theplurality of optical elements and members for constructing the lightreceiver 290. In the spatial image-measuring unit 270 shown in FIG. 25,the space between the slit plate 275 and the light receiver 290 isfilled with the liquid LQ. In this embodiment, the space, which isfilled with the liquid LQ, is disposed between the lower surface of theslit plate 275 fitted to the opening 284 of the projection 283 and theoptical element 276 arranged at the position nearest to the slit plate275, of the plurality of optical elements (optical members) arranged onthe optical path of the light receiver 290. The optical element 276 isretained by the holding member 285 attached to the inner wall surface283A of the projection 283 at the position under the slit plate 275. Thespace SP, which is surrounded by the slit plate 275, the holding member285, and the optical element 276, is filled with the liquid LQ. In thisembodiment, the optical element 276 is composed of a plano-convex lens,which is arranged such that the flat surface thereof is directedupwardly. The inner bottom surface 285A of the holding member 285 issubstantially flush with the upper surface (flat surface) 276A of theoptical element 276. The holding member 285 is formed to have a ]-shapedform (like a shape of staple) directed substantially upwardly as viewedin a sectional view. The outer side surface 285B of the holding member285 makes tight contact with the inner wall surface 283A of theprojection 283. A seal member 291 such as an O-ring is provided betweenthe slit plate 275 and the upper end surface (joining surface withrespect to the slit plate 275) 285C of the holding member 285.Accordingly, the inconvenience is avoided, which would be otherwisecaused such that the liquid LQ with which the space SP is filled leaksto the outside.

The slit plate 275 and the holding member 285 which retains the opticalelement 276 are detachable with respect to the inner wall surface 283Aof the projection 283. When the holding member 285 is attached, then theholding member 285, which retains the optical element 276, is insertedinto the projection 283 from the opening 284 of the projection 283 (inthis situation, the slit plate 275 is not attached), and the holdingmember 285 and the inner wall surface 283A of the projection 283 arefixed by an unillustrated fixing member. Subsequently, the slit plate275 is fitted to the opening 284. On the other hand, when the holdingmember 285 is detached, it is appropriate that the slit plate 275 isremoved from the opening 284, and then the holding member 285 is pulledout via the opening 284.

The exposure apparatus EX further comprises a liquid supply unit 300which supplies the liquid LQ to the space SP between the slit plate 275and the optical element 276 of the light receiver 290, and a liquidrecovery unit 304 which recovers the liquid LQ from the space SP. Asupply flow passage 302, which is connected to the space SP, is formedthrough the wall portions of the projection 283 and the holding member285 disposed on the +X side. A recovery flow passage 306, which isconnected to the space SP, is formed through the wall portions disposedon the −X side. One end of a supply tube 301 is connected to the liquidsupply unit 300, and the other end of the supply tube 301 is connectedto the supply flow passage 302 by the aid of a joint 303. One end of arecovery tube 305 is connected to the liquid recovery unit 304, and theother end of the recovery tube 305 is connected to the recovery flowpassage 306 by the aid of a joint 307. Valves 301A, 305A, whichopen/close the flow passages, are provided at intermediate positions ofthe supply tube 301 and the recovery tube 305 respectively. Theoperations of the liquid supply unit 300, the liquid recovery unit 304,and the valves 301A, 305A are controlled by the control unit CONT. Thecontrol unit CONT controls these components to supply and recover theliquid LQ with respect to the space SP, and thus the space SP is filledwith the liquid LQ.

As shown in FIG. 26, the slit plate 275 includes a light-shielding film272 which is composed of chromium or the like and which is provided atthe central portion of the upper surface of the glass place member 274that is rectangular as viewed in a plan view, a reflective film 273which is composed of aluminum or the like and which is provided aroundthe light-shielding film 272, i.e., at the portions of the upper surfaceof the glass plate member 274 except for the light-shielding film 272,and the slit section 271 which is an aperture pattern formed at a partof the light-shielding film 272. The glass plate member 274, which is atransparent member, is exposed at the slit section 271. The light beamis transmissive through the slit section 271. The slit section 271 is arectangular (oblong) slit in which the Y axis direction is thelongitudinal direction. The slit section 271 has a predetermined width2D.

Next, an explanation will be made about the procedure for measuring theimaging characteristic of the projection optical system PL by using thespatial image-measuring unit 270 as described above.

When the spatial image (projection image) is measured, the control unitCONT moves the substrate stage PST so that the projection optical systemPL is opposed to the slit plate 275 (in other words, the state shown inFIG. 24 is established). The liquid supply mechanism 210 and the liquidrecovery mechanism 220 are used to fill, with the liquid LQ, the spacebetween the slit plate 275 and the optical element 260 disposed at theend portion of the projection optical system PL. Concurrently with thisoperation (or before or after this operation), the control unit CONTuses the liquid supply unit 300 and the liquid recovery unit 304 tofill, with the liquid LQ, the space between the slit plate 275 and theoptical element 276 of the light receiver 290 as shown in FIG. 25. Inthe following description, the liquid immersion area, which is formed byfilling, with the liquid LQ, the space between the projection opticalsystem PL and the slit plate 275, is appropriately referred to as “firstliquid immersion area LA1”, and the liquid immersion area, which isformed by filling, with the liquid LQ, the space between the slit plate275 and the light receiver 290 (optical element 276), is appropriatelyreferred to as “second liquid immersion area LA2”.

When the spatial image is measured, the mask M provided with themeasuring mark as described later on is supported on the mask stage MST.The control unit CONT illuminates the mask M with the exposure beam ELby the illumination optical system IL. The light beam (exposure beamEL), which passes through the measuring mark, the projection opticalsystem PL, and the liquid LQ in the first liquid immersion area LA1, isradiated onto the slit plate 275. The light beam, which has passedthrough the slit section 271 of the slit plate 275, comes into theoptical element 276 through the liquid LQ in the second liquid immersionarea LA2.

The numerical aperture NA of the projection optical system is improvedby the liquid LQ in the first liquid immersion area LA1 between theprojection optical system PL and the slit plate 275. Therefore, if thenumerical aperture NA of the optical element 276 of the light receiver290 is not improved in response to the numerical aperture NA of theprojection optical system PL, then there is such a possibility that theoptical element 276 cannot satisfactorily import or incorporate (all of)the light beam which has passed through the projection optical systemPL, and it is impossible to receive the light beam in a well-suitedmanner. Accordingly, when the numerical aperture NA of the projectionoptical system PL is improved by filling, with the liquid LQ, the spacebetween the projection optical system PL and the slit plate 275 as inthis embodiment, the space between the slit plate 275 and the opticalelement 276 of the light receiver 290 is also filled with the liquid LQto improve the numerical aperture NA of the optical element 276 of thelight receiver 290. Thus, the optical element 276 of the light receiver290 can satisfactorily import the light beam which has passed throughthe projection optical system PL.

The optical element 276 collects the light beam which has passed throughthe second liquid immersion area LA2. The light beam, which is collectedby the optical element 276, passes along the mirror 277, the opticalelement 278, and the light-feeding lens 279, and the light beam is ledto the outside of the substrate stage PST (FIG. 23). The optical path isbent by the mirror 280 for the light beam having been led to the outsideof the substrate stage PST. The light beam passes through thelight-receiving lens 281, and the light beam is received by the opticalsensor 282. The photoelectric conversion signal (light amount signal),which corresponds to the light-receiving amount, is outputted from theoptical sensor 282 via the signal processing unit to the control unitCONT.

In this embodiment, the projection image (spatial image) of themeasuring mark is measured in the slit scan manner as described lateron. Therefore, during this process, the light-feeding lens 279 is movedwith respect to the light-receiving lens 281 and the optical sensor 282.Accordingly, in the case of the spatial image-measuring unit 270, thesizes of the respective lenses and the mirror 280 are designed so thatall of the light beam, which passes through the light-feeding lens 279that is movable within a predetermined range, comes into thelight-receiving lens 281.

In the case of the spatial image-measuring unit 270, the optical sensor282 is provided at the predetermined position outside the substratestage PST. Therefore, the influence exerted, for example, on themeasurement accuracy of the laser interferometer 244, which is caused bythe heat generation by the optical sensor 282, is suppressed within afeasible range. Further, the outside and the inside of the substratestage PST are not connected by any light guide or the like. Therefore,the driving accuracy of the substrate stage PST is not affected unlikethe case in which the outside and the inside of the substrate stage PSTare connected by the light guide. Of course, the optical sensor 282 maybe provided inside the substrate stage PST, when the influence of theheat or the like can be neglected or excluded. That is, parts of theplurality of optical elements and light-receiving elements forconstructing the light receiver 290 may be provided on the substratestage PST, or all of them may be provided on the substrate stage PST.

In this embodiment, those usable as the liquid LQ for the “first liquidimmersion area LA1” and the “second liquid immersion area LA2” may be aliquid of the same type or liquids of different types, especiallyliquids having different refractive indexes with respect to the exposurebeam. In particular, it is preferable that the liquid, which is used forthe “first liquid immersion area LA1”, is selected in consideration ofNA or the refractive index of the optical element provided at the endportion of the projection optical system. On the other hand, the liquid,which is used for the “second liquid immersion area LA2”, can beselected in consideration of the refractive index of the glass platemember 274 and/or the size and the refractive index of the opticalelement 276.

This embodiment has been explained about the example wherein the spatialimage-measuring unit 270, in which the space between the slit plate 275and the light receiver 290 (optical element 276) is filled with theliquid LQ, is applied to the liquid immersion exposure apparatus.However, the spatial image-measuring unit 270 (light receiver 290)according to the present invention can be also applied to a dry exposureapparatus (ordinary exposure apparatus) in which the exposure isperformed while the space between the projection optical system PL andthe substrate P is not filled with the liquid LQ. When the spatial imageis measured in the dry exposure apparatus, the exposure beam EL, whichhas passed through the projection optical system PL, is radiated ontothe slit plate 275 in a state in which the projection optical system PLand the slit plate 275 are opposed to one another on condition that thespace between the projection optical system PL and the slit plate 275 isnot filled with the liquid LQ and the space between the slit plate 275and the optical element 276 of the light receiver 290 is filled with theliquid LQ (on condition that the first liquid immersion area LA1 is notformed and only the second liquid immersion area LA2 is formed). Theoptical element 276 of the light receiver 290 undergoes the improvementin the numerical aperture NA owing to the liquid LQ with which the spacebetween the slit plate 275 and the optical element 276 is filled.Therefore, the light beam can be satisfactorily received even in thecase of the dry exposure apparatus which is provided with the projectionoptical system having the large numerical aperture NA (for example,NA>0.9). The light beam, which has passed through the projection opticalsystem PL, can be also received satisfactorily, for example, by allowingthe optical element 276 of the light receiver 290 to make tight contactwith the slit plate 275. An effect is obtained such that the entirelight receiver 290 can be made compact.

In this embodiment, the space SP between the slit plate 275 and theoptical element 276 is filled with the liquid LQ by supplying andrecovering the liquid LQ by using the liquid supply unit 300 and theliquid recovery unit 304. However, the space SP can be also filled withthe liquid LQ, for example, upon the production of the exposureapparatus EX without using the liquid supply unit 300 and the liquidrecovery unit 304. In this case, for example, the slit plate 275 may bedetached from the projection 283 (Z tilt stage 252), and the liquid LQin the space SP may be periodically exchanged. Alternatively, a liquid,which is excellent in storage performance and which requires noexchange, may be used as the liquid LQ. On the other hand, the space SPcan be always filled with the fresh (clean) liquid LQ by supplying andrecovering the liquid LQ by using the liquid supply unit 300 and theliquid recovery unit 304. The liquid supply operation and the liquidrecovery operation of the liquid supply unit 300 and the liquid recoveryunit 304 may be stopped during the measurement with the spatialimage-measuring unit 270. For example, when the holding member 285,which retains the slit plate 275 and the optical element 276, isdetached from the projection 283 (Z tilt stage 252), theattachment/detachment operation can be performed without causing anyleakage of the liquid LQ by detaching the holding member 285 whichretains the optical element 276 and the slit plate 275 after recoveringthe liquid LQ from the space SP by using the liquid recovery unit 304.

A light-transmissive member (optical member, glass member), which hasapproximately the same refractive index as that of the liquid LQ, may bearranged between the slit plate 275 and the light receiver 290 (opticalelement 276) without filling the space between the slit plate 275 andthe light receiver 290 (optical element 276) with the liquid LQ. Such alight-transmissive member includes, for example, quartz and fluorite. Inthis embodiment, the liquid LQ is pure water. It is approved that therefractive index of pure water with respect to the ArF excimer laserlight beam is approximately 1.44. On the other hand, it is approved thatthe refractive index of quartz with respect to the ArF excimer laserlight beam is approximately 1.56. Therefore, a light-transmissive membercomposed of quartz may be arranged between the slit plate 275 and theoptical element 276 in place of the formation of the second liquidimmersion area LA2 with the liquid (pure water) LQ.

An exemplary operation for measuring the spatial image based on the useof the spatial image-measuring unit 270 will be explained below, forexample, with reference to FIG. 24. As described above, FIG. 24 showsthe state in which the spatial image is measured. Those usable as themask M during the spatial image measurement include, for example, thosewhich are exclusively used to measure the spatial image, and thoseobtained by forming exclusive measuring marks on the mask for producingthe device to be used to produce the device. Alternatively, it is alsoallowable to use the following material in place of the mask asdescribed above. That is, a fixed mark plate (reference mark plate),which is composed of a glass material having the same quality as that ofthe mask, is provided on the mask stage MST, and a measuring mark isformed on the mark plate.

A measuring mark PMx (FIG. 24) and a measuring mark PMy (FIG. 24) areformed at predetermined positions on the mask M so that they aredisposed closely to one another. The measuring mark PMx is composed of aline-and-space (L/S) mark which has the periodicity in the X axisdirection and which has a ratio (duty ratio) of 1:1 between the width ofthe line portion and the width of the space portion. The measuring markPMy is composed of an L/S mark which has the periodicity in the Y axisdirection and which has a duty ratio of 1:1. Each of the measuring marksPMx, PMy is composed of a line pattern having the same line width. Asshown in FIG. 27A, the slit plate 275, which constitutes the spatialimage-measuring unit 270, is provided with a slit section 271 x whichhas a predetermined width 2D and which extends in the Y axis directionand a slit section 271 y which has a predetermined width 2D and whichextends in the X axis direction, the slit section 271 x and the slitsection 271 y being formed in a predetermined positional relationship asshown in FIG. 27A. As described above, for example, a plurality of slitsections 271 x, 271 y are actually formed for the slit plate 275.However, the slit sections are represented by the slit section 271 asdepicted, for example, in FIGS. 20 to 26.

For example, when the spatial image of the measuring mark PMx ismeasured, then the movable mask blind 207B shown in FIG. 20 is driven bythe control unit CONT by the aid of the unillustrated blind-drivingunit, and the illumination area of the exposure beam EL is restricted tobe a predetermined area including the portion of the measuring mark PMx.When the control unit CONT starts the light emission of the light source201 in this state, and the exposure beam EL is radiated onto themeasuring mark PMx, then the light beam (exposure beam EL), which isdiffracted and scattered by the measuring mark PMx, is refracted by theprojection optical system PL, and the spatial image (projection image)of the measuring mark PMx is formed on the image plane of the projectionoptical system PL. In this situation, it is assumed that the substratestage PST is provided at the position at which the spatial image PMx′ ofthe measuring mark PMx is formed on the +X side (or −X side) of the slitsection 271 x on the slit plate 275 as shown in FIG. 27A.

When the substrate stage PST is driven in the +X direction as shown bythe arrow Fx in FIG. 27A by the substrate stage-driving unit PSTD underthe instruction of the control unit CONT, the slit section 271 x isscanned in the X axis direction with respect to the spatial image PMx′.The light beam (exposure beam EL), which passes through the slit section271 x during the scanning, is received by the optical sensor 282 via thelight-receiving optical system in the substrate stage PST (Z tilt stage252), the mirror 280 disposed outside the substrate stage PST, and thelight-receiving lens 281. The photoelectric conversion signal thereof issupplied to the signal processing unit. The signal processing unitapplies the predetermined processing to the photoelectric conversionsignal, and the light intensity signal corresponding to the spatialimage PMx′ is supplied to the control unit CONT. During this process, inorder to suppress the influence caused by any dispersion of the lightemission intensity of the exposure beam EL supplied from the lightsource 201, the signal, which is obtained by normalizing the signal fromthe optical sensor 282 with the signal from the integrator sensor 233shown in FIG. 20, is supplied by the signal processing unit to thecontrol unit CONT. FIG. 27B shows an example of the photoelectricconversion signal (light intensity signal) obtained when the spatialimage is measured as described above.

When the spatial image of the measuring mark PMy is measured, then thesubstrate stage PST is provided at the position at which the spatialimage of the measuring mark PMy is formed on the +Y side (or on the −Yside) of the slit section 271 y on the slit plate 275, and themeasurement is performed in the slit scan manner in the same manner asdescribed above. Accordingly, it is possible to obtain the photoelectricconversion signal (light intensity signal) corresponding to the spatialimage of the measuring mark PMy. The measuring mark is not limited tothe mark as described above, which may be appropriately determineddepending on, for example, the measurement accuracy and the imagingcharacteristic of the measurement objective.

When the measurement is performed in order to obtain, for example, theinformation about the adjustment of the imaging characteristic, thefocus of the projection optical system PL and another predeterminedimaging characteristic (for example, at least one of various aberrationssuch as the field curvature, the magnification, the distortion, thecomatic aberration, and the spherical aberration) are measured by usingthe spatial image-measuring unit 270 (FIG. 20) as described later on,while the optical elements 264 a, 264 b are driven one by one, and whilethe pressures of the first and second tightly closed chambers 265A, 265Bare changed one by one, firstly upon the initial adjustment as shown inFIG. 21 to determine the amounts of the imaging characteristic changewith respect to the driving amounts of the optical elements 264 a, 264 band the pressure changes in the first and second tightly closed chambers265A, 265B.

An explanation will be made below about a method for detecting the bestfocus position of the projection optical system PL as an example of theoperation for measuring the imaging characteristic. In this procedure,it is premised that the ordinary diaphragm of the illumination systemaperture diaphragm plate 204 is selected, and the ordinary illuminationcondition is established as the illumination condition. For example, amask M, which is formed with a measuring mark PMx (or PMy) composed ofan L/S pattern having a duty ratio of 50% and a line width of 1 μm, isused to detect the best focus position. At first, the mask M is loadedon the mask stage MST by an unillustrated loader unit. Subsequently, thecontrol unit CONT moves the mask stage MST by the aid of the maskstage-driving unit MSTD so that the measuring mark PMx on the mask M isapproximately coincident with the optical axis of the projection opticalsystem PL. Subsequently, the control unit CONT defines the illuminationarea by driving and controlling the movable mask blind 207B so that theexposure beam EL is radiated onto only the portion of the measuring markPMx. The control unit CONT radiates the exposure beam EL onto the mask Min this state to measure the spatial image of the measuring mark PMx inthe slit scan manner by using the spatial image-measuring unit 270 whilescanning the substrate stage PST in the X axis direction in the samemanner as described above. During this process, control unit CONTrepeats the measurement of the spatial image of the measuring mark PMx aplurality of times while changing, at a predetermined step pitch, theposition of the slit plate 275 in the Z axis direction (i.e., theposition of the Z tilt stage 252) by the aid of the substratestage-driving unit PSTD, and the light intensity signals (photoelectricconversion signals), which are obtained by the respective repetitions,are stored in the memory unit MRY. The position of the slit plate 275 inthe Z axis direction is changed by controlling the actuators 259A, 259B,2590 on the basis of the measured values of the encoders 258A, 258E,258C for the Z tilt stage 252. The control unit CONT performs theFourier transformation for the plurality of light amount signals(photoelectric conversion signals) obtained by the repetitions asdescribed above respectively to determine the contrast which is theamplitude ratio between the 1st order frequency component and the0-order frequency component of each of them. The control unit CONTdetects the Z position of the Z tilt stage 252 (i.e., the position ofthe slit plate 275 in the Z axis direction) corresponding to the lightintensity signal at which the contrast is maximized. This position isdetermined as the best focus position of the projection optical systemPL. The contrast sensitively changes depending on the focus position(defocus amount). Therefore, it is possible to measure (determine) thebest focus position of the projection optical system PL accurately withease. The control unit CONT performs the focus calibration to reset(calibrate) the detection origin (detection reference point) of thefocus-detecting system 245 on the basis of the determined best focusposition. Accordingly, the predetermined surface on the substrate stagePST (for example, the surface of the substrate P or the surface of theslit plate 275) can be thereafter positioned at the position which isoptically conjugate with the reference plane of the mask M by thefocus-detecting system 245.

The amplitudes of the frequency components of the 2nd order or higherorder real numbers are generally small, and the amplitudes cannot beobtained sufficiently with respect to the electric noise and the opticalnoise in some cases. However, when no problem arises in view of the S/Nratio (signal/noise ratio), the best focus position can be alsodetermined by observing the change of the amplitude ratios of the higherorder frequency components. There is no limitation to the method basedon the use of the contrast. The best focus position can be also detectedby a technique to detect the Z position (focus position) at which thederivative value of the light intensity signal is maximized.

The explanation has been made in this case about the method (slit scansystem) in which the slit section 271 (slit plate 275) is scanned in thepredetermined direction in the XY plane when the best focus position ofthe projection optical system PL is measured. However, the followingprocedure is also available. That is, a spatial image of a measuringmark such as an isolated line mark is formed on the image plane of theprojection optical system PL. The slit plate 275 (Z tilt stage 252) isscanned (subjected to the scanning) in the Z axis direction within apredetermined stroke range about the center of the best focus positionso that the slit section 271 (slit plate 275) is scanned in thedirection of the optical axis AX (Z axis direction) relative to thespatial image. The best focus position is determined on the basis of thelight intensity signal (peak value) obtained in the situation asdescribed above. In this procedure, it is preferable to use themeasuring mark with which the spatial image of the measuring mark has,on the image plane, a dimension and a shape approximately coincidentwith the shape of the slit section 271 (271 x or 271 y). When thespatial image is measured as described above, it is possible to obtainthe light intensity signal as shown in FIG. 26. In this case, theposition of the peak of the signal waveform of the light intensitysignal may be directly found out, and thus the Z position of the pointmay be regarded as the best focus position Z₀. Alternatively, the lightintensity signal may be sliced by using a predetermined slice level lineSL, and the Z position of the midpoint between the two points ofintersection of the light intensity signal and the slice level line SLmay be regarded as the best focus position Z₀. In any case, this methodmakes it possible to detect the best focus position by scanning the slitplate 275 in the Z axis direction only once. Therefore, it is possibleto improve the throughput.

Next, an explanation will be made about a method for detecting the imageplane shape of the projection optical system PL (field curvature) as anexample of the operation for measuring the imaging characteristic. Whenthe field curvature is detected, a mask M1 is used as shown in FIG. 29by way of example, wherein measuring marks PM₁ to PM_(n), each of whichhas the same dimension and the same cycle as those of the measuring markPMx described above, are formed in a pattern area PA. After the mask M1is loaded on the mask stage MST, the control unit CONT moves the maskstage MST by the aid of the mask stage-driving unit MSTD so that themeasuring mark PM_(k), which is disposed at the center of the mask M1,is approximately coincident with the optical axis of the projectionoptical system PL. That is, the mask M1 is positioned with respect tothe reference point. It is assumed that all of the measuring marks PM₁to PM_(n) are positioned in the field of the projection optical systemPL when the positioning has been performed with respect to the referencepoint.

Subsequently, the control unit CONT defines the illumination area bydriving and controlling the movable mask blind 207B so that the exposurebeam EL is radiated onto only the portion of the PM₁. The control unitCONT radiates the exposure beam EL onto the mask M1 in this state tomeasure the spatial image of the measuring mark PM₁ and detect the bestfocus position of the projection optical system PL by using the spatialimage-measuring unit 270 in the slit scan manner in the same manner asdescribed above. The obtained result is stored in the memory unit MRY.When the detection of the best focus position based on the use of themeasuring mark PM₁ is completed, the control unit CONT defines theillumination area by driving and controlling the movable mask blind 207Bso that the exposure beam EL is radiated onto only the portion of themeasuring mark PM₂. In this state, the spatial image is measured for themeasuring mark PM₂, and the best focus position of the projectionoptical system PL is detected in the slit scan manner in the same manneras described above. The obtained result is stored in the memory unitMRY. After that, the control unit CONT repeatedly performs themeasurement of the spatial image and the detection of the best focusposition of the projection optical system PL for the measuring marks PM₃to PM_(n) while changing the illumination area in the same manner asdescribed above. The control unit CONT performs the predeterminedstatistical processing on the basis of the respective best focuspositions Z₁, Z₂, . . . , Z_(n) obtained as described above.Accordingly, the field curvature of the projection optical system PL iscalculated.

When the spherical aberration of the projection optical system PL isdetected, a mask M2 shown in FIG. 30 is used. Two measuring marks PM1,PM2, which are separated from each other by a predetermined distance inthe X axis direction, are formed at approximately central portions inthe Y axis direction in a pattern area PA of the mask M2 shown in FIG.30. The measuring mark PM1 has an L/S pattern having the same dimensionand the same cycle as those of the measuring mark PMx described above.The measuring mark PM2 has an L/S pattern in which a line pattern havingthe same dimension as that of the measuring mark PMx is aligned in the Xaxis direction at a different cycle (for example, about 1.5 to 2 timesthe cycle (mark pitch) of the measuring mark PM1). After the mask M2 isloaded on the mask stage MST, the control unit CONT moves the mask stageMST by the aid of the mask stage-driving unit MSTD so that the measuringmark PM1 on the mask M2 is approximately coincident with the opticalaxis of the projection optical system PL. Subsequently, the control unitCONT defines the illumination area by driving and controlling themovable mask blind 207B so that the exposure beam EL is radiated ontoonly the portion of the measuring mark PM1. The control unit CONTradiates the exposure beam EL onto the mask M2 in this state to measurethe spatial image of the measuring mark PM1 and detect the best focusposition of the projection optical system PL by using the spatialimage-measuring unit 270 in the slit scan manner in the same manner asdescribed above. The obtained result is stored in the memory unit MRY.When the detection of the best focus position based on the use of themeasuring mark PM1 is completed, the control unit CONT moves the maskstage MST by the predetermined distance in the −X direction by the aidof the mask stage-driving unit MSTD so that the exposure beam EL isradiated onto the measuring mark PM2. The spatial image of the measuringmark PM2 is measured, and the best focus position of the projectionoptical system PL is detected in this state in the slit scan manner inthe same manner as described above. The obtained result is stored in thememory unit MRY. The control unit CONT calculates the sphericalaberration of the projection optical system PL by calculation on thebasis of the difference between the respective obtained best focuspositions Z₁ and Z₂.

When the magnification and the distortion of the projection opticalsystem PL are detected, a mask M3 shown in FIG. 31 is used. A total offive measuring marks BM₁ to BM₅, each of which is composed of, forexample, a square mark of 120 μm square (30 μm square on the slit plate275 at a projection magnification of ¼), are formed at a central portionand four corners of a pattern area PA of the mask M3 shown in FIG. 31.After the mask M3 is loaded on the mask stage MST, the control unit CONTmoves the mask stage MST by the aid of the mask stage-driving unit MSTDso that the center of the measuring mark BM₁ existing at the center ofthe mask M3 is approximately coincident with the optical axis of theprojection optical system PL. That is, the mask M3 is positioned withrespect to the reference point. It is assumed that all of the measuringmarks BM₁ to BM₅ are positioned in the field of the projection opticalsystem PL in the state in which the positioning has been performed withrespect to the reference point. Subsequently, the control unit CONTdefines the illumination area by driving and controlling the movablemask blind 207B so that the exposure beam EL is radiated onto only arectangular area portion which includes the measuring mark BM₁ and whichis larger than the measuring mark BM₁ as a whole. In this state, thecontrol unit CONT radiates the exposure beam EL onto the mask M3.Accordingly, the spatial image of the measuring mark BM₁, i.e., the markimage having a square shape of approximately 30 μm square is formed. Inthis state, the control unit CONT measures the spatial image of themeasuring mark BM₁ by using the spatial image-measuring unit 270 whilescanning the substrate stage PST in the X axis direction by the aid ofthe substrate stage-driving unit PSTD. The light intensity signalobtained by the measurement is stored in the memory unit MRY.Subsequently, the control unit CONT determines the imaging position ofthe measuring mark BM₁ on the basis of the obtained light intensitysignal, for example, in accordance with the known technique of the phasedetection or the technique of the edge detection. For example, thefollowing general method can be used for technique of the phasedetection. That is, the control unit CONT determines a sum correspondingto, for example, one cycle of a product of a 1st order frequencycomponent (regarded as sine wave) obtained by performing the Fouriertransformation for the light intensity signal and a sine wave to serveas the reference for the same frequency as the above, and the controlunit CONT determines a sum corresponding to, for example, one cycle of aproduct of the 1st order frequency component and a cosine wave to serveas the reference for the same cycle as the above. The control unit CONTdetermines an arctangent of a quotient obtained by dividing the obtainedsums to one another. Accordingly, the control unit CONT determines thephase difference of the 1st frequency component with respect to thereference signal. The X position x₁ of the measuring mark BM₁ isdetermined on the basis of the phase difference. On the other hand, atechnique of the edge detection based on the slice method can be used asthe technique of the edge detection in which the positions of the edgesof the spatial image corresponding to each of the photoelectricconversion signals are calculated respectively on the basis of thepoints of intersection between the light intensity signal and apredetermined slice level. Subsequently, the control unit CONT measuresthe spatial image of the measuring mark BM₁ by using the spatialimage-measuring unit 270 while scanning the substrate stage PST in the Yaxis direction. The light intensity signal obtained by the measurementis stored in the memory unit MRY. The Y position y₁ of the measuringmark BM₁ is determined, for example, in accordance with the technique ofthe phase detection in the same manner as described above. The controlunit CONT corrects the positional deviation of the mask M3 with respectto the center of the optical axis on the basis of the obtainedcoordinate position (x₁, y₁) of the measuring mark BM₁. When thecorrection of the positional deviation of the mask M3 is completed, thecontrol unit CONT defines the illumination area by driving andcontrolling the movable mask blind 207B so that the exposure beam EL isradiated onto only a rectangular area portion which includes themeasuring mark BM₂ and which is larger than the measuring mark BM₂ as awhole. In this state, the measurement of the spatial image of themeasuring mark BM₂ and the measurement of the XY position are performedin the slit scan manner in the same manner as described above. Theobtained result is stored in the memory unit MRY. After that, thecontrol unit CONT repeatedly performs the measurement of the spatialimage and the measurement of the XY position for the measuring marks BM₃to BM₅ while changing the illumination area. The predeterminedcalculation is performed on the basis of the coordinate values (x₂, y₂)(x₃, y₃), (x₄, y₄), (x₅, y₅) of the measuring marks BM₂ to BM₅ obtainedas described above. Accordingly, the control unit CONT calculates atleast one of the magnification and the distortion of the projectionoptical system PL.

The explanation has been made above by way of example about theprocedure for measuring the best focus position, the field curvature,the spherical aberration, the magnification, and the distortion of theprojection optical system PL by using the spatial image-measuring unit270. The spatial image-measuring unit 270 is also capable of measuring,for example, other imaging characteristics including, for example, thecomatic aberration by using a predetermined measuring mark.

As described above, when the imaging characteristic of the projectionoptical system PL is measured in the slit scan manner, the light beam isradiated onto the light receiver 290 (optical element 276) through theliquid LQ while moving the slit plate 275 (slit section 271) relative tothe light beam (exposure beam EL) which has passed through theprojection optical system PL.

The control unit CONT determines the correction amounts to obtain thedesired imaging characteristic, specifically the driving amounts of theoptical elements 264 a, 264 b of the projection optical system PL andthe adjustment amounts of the internal pressures of the first and secondtightly closed chambers 265A, 265B on the basis of the information aboutthe imaging characteristic of the projection optical system PL measuredas described above. In this procedure, the memory unit MRY stores therelationship (i.e., the imaging characteristic adjustment information)between the change amounts (variation amounts) of various types of theimaging characteristics of the projection optical system PL and thedriving amounts of the optical elements 264 a, 264 b of the projectionoptical system PL and the adjustment amounts of the internal pressuresof the first and second tightly closed chambers 265A, 265B previouslydetermined, for example, by an experiment or simulation. The controlunit CONT makes reference to the relationship stored in the memory unitMRY to determine the correction amounts including the driving amounts ofthe optical elements 264 a, 264 b of the projection optical system PLand the adjustment amounts of the internal pressures of the first andsecond tightly closed chambers 265A, 265B in order that the imagingcharacteristic of the projection optical system PL is corrected to be inthe desired state. Details of the spatial image measurement aredisclosed, for example, in Japanese Patent Application Laid-open No.2002-14005 (corresponding to United States Patent Publication No.2002/0041377). The disclosures thereof are incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

An explanation will be made about the procedure for exposing thesubstrate P with a pattern for producing a device by using the exposureapparatus EX.

As shown in FIG. 20, the imaging characteristic is measured via theprojection optical system PL and the liquid LQ by using the spatialimage-measuring unit 270, and the correction amounts are derived inorder to correct the imaging characteristic. After that, the controlunit CONT drives the substrate stage PST by the aid of the substratestage-driving unit PSTD so that the projection optical system PL isopposed to the substrate P loaded on the substrate stage PST. In thissituation, the mask M, on which the pattern for the device production isformed, is loaded on the mask stage MST. The control unit CONT drivesthe liquid supply section 211 of the liquid supply mechanism 210 tosupply, onto the substrate P, the liquid LQ in the predetermined amountper unit time by the aid of the supply tube 212 and the supply nozzles213. Further, the control unit CONT drives the liquid recovery section(vacuum system) 221 of the liquid recovery mechanism 220 in accordancewith the supply of the liquid LQ by the liquid supply mechanism 210 torecover the liquid LQ in the predetermined amount per unit time by theaid of the recovery nozzles 223 and the recovery tube 222. Accordingly,the liquid immersion area AR2 of the liquid LQ is formed between thesubstrate P and the optical element 260 disposed at the end portion ofthe projection optical system PL.

The control unit CONT drives the illumination optical system IL toilluminate the mask M with the exposure beam EL, and the image of thepattern of the mask M is projected onto the substrate P via theprojection optical system PL and the liquid LQ. In this procedure, whenthe exposure process is performed for the substrate P, the control unitCONT performs the exposure process while adjusting the imagingcharacteristic via the projection optical system PL and the liquid LQ bydriving the optical elements 264 a, 264 b of the projection opticalsystem PL and/or adjusting the internal pressures of the first andsecond tightly closed chambers 265A, 265B on the basis of the correctionamounts determined as described above (FIG. 21).

During the scanning exposure, a part of the image of the pattern of themask M is projected onto the projection area AR1. The mask M is moved atthe velocity V in the −X direction (or in the +X direction) with respectto the projection optical system PL, in synchronization with which thesubstrate P is moved at the velocity β·V (β represents the projectionmagnification) in the +X direction (or in the −X direction) by the aidof the substrate stage PST. After the exposure is completed for one shotarea, the next shot area is moved to the scanning start position inaccordance with the stepping movement of the substrate P. The exposureprocess is successively performed thereafter for the respective shotareas in the step-and-scan manner. This embodiment is established suchthat the liquid LQ is allowed to flow in parallel to the direction ofmovement of the substrate P in the same direction as the direction ofmovement of the substrate P. In other words, when the scanning exposureis performed while moving the substrate P in the scanning direction (−Xdirection) indicated by the arrow Xa (see FIG. 22), the supply tube 212,the supply nozzles 213A to 213C, the recovery tube 222, and the recoverynozzles 223A, 223B are used to supply and recover the liquid LQ by theliquid supply mechanism 210 and the liquid recovery mechanism 220. Thatis, when the substrate P is moved in the −X direction, then the liquidLQ is supplied to the space between the projection optical system PL andthe substrate P by the supply nozzles 213 (213A to 213C), and the liquidLQ is recovered from the surface of the substrate P by the recoverynozzles 223 (223A, 223B). The liquid LQ is allowed to flow in the −Xdirection so that the space between the substrate P and the opticalelement 260 disposed at the end portion of the projection optical systemPL is filled therewith. On the other hand, when the substrate P is movedin the scanning direction (+X direction) indicated by the arrow Xb (seeFIG. 22) to perform the scanning exposure, the supply tube 215, thesupply nozzles 216A to 216C, the recovery tube 225, and the recoverynozzles 226A, 2263 are used to supply and recover the liquid LQ by theliquid supply mechanism 210 and the liquid recovery mechanism 220. Thatis, when the substrate P is moved in the +X direction, then the liquidLQ is supplied to the space between the projection optical system PL andthe substrate P by the supply nozzles 216 (216A to 216C), and the liquidLQ is recovered from the surface of the substrate P by the recoverynozzles 226 (226A, 226B). The liquid LQ is allowed to flow in the +Xdirection so that the space between the substrate P and the opticalelement 260 disposed at the end portion of the projection optical systemPL is filled therewith. In this procedure, for example, the liquid LQ,which is supplied via the supply nozzles 213, flows so that the liquidLQ is attracted and introduced into the space between the opticalelement 260 and the substrate P in accordance with the movement of thesubstrate P in the −X direction. Therefore, even when the supply energyof the liquid supply mechanism 210 (liquid supply section 211) is small,the liquid LQ can be easily supplied to the space between the opticalelement 260 and the substrate P. When the direction of the flow of theliquid LQ is switched depending on the scanning direction, the spacebetween the optical element 260 and the substrate P can be filled withthe liquid LQ even when the substrate P is subjected to the scanning inany one of the +X direction and the −X direction. It is possible toobtain the high resolution and the wide depth of focus.

In the embodiment described above, the liquid is supplied by the liquidsupply mechanism 210 and the liquid is recovered by the liquid recoverymechanism 220 during the measuring operation performed by the spatialimage-measuring unit 270 so that the liquid LQ flows between the slitplate 275 and the optical element 260 of the projection optical systemPL. However, when the radiation of the light beam scarcely causes thetemperature change of the liquid LQ and the deterioration of the liquidLQ, it is also allowable to adopt the following procedure. That is, theliquid LQ is supplied by the liquid supply mechanism 210 before themeasurement. Both of the operations of the liquid supply by the liquidsupply mechanism 210 and the liquid recovery by the liquid recoverymechanism 220 are stopped during the measuring operation. The liquid LQis recovered by the liquid recovery mechanism 220 after the completionof the measuring operation.

Twelfth Embodiment

A twelfth embodiment of the present invention will be explained below.In the following description, the constitutive portions, which are thesame as or equivalent to those of the eleventh embodiment describedabove, are designated by the same reference numerals, any explanation ofwhich will be simplified or omitted.

FIG. 32 shows another embodiment of the spatial image-measuring unit270. With reference to FIG. 32, the optical sensor 282, which isincluded in the light receiver 290 of the spatial image-measuring unit270, is arranged at a position nearest to the slit plate 275. The spaceSP between the optical sensor 282 and the slit plate 275 is filled withthe liquid LQ. The optical sensor 282 is retained by the holding member285. The light-receiving surface 282A of the optical sensor 282 is flushwith the inner bottom surface 285A of the holding member 285. Even whenthe arrangement as described above is adopted, the optical sensor 282can satisfactorily receive the light beam which has passed through theprojection optical system PL, the first liquid immersion area LA1, theslit plate 275, and the second liquid immersion area LA2.

Thirteenth Embodiment

FIG. 33 shows another embodiment of the spatial image-measuring unit270. As shown in FIG. 33, the light-receiving surface 282A of theoptical sensor 282 makes tight contact with the lower surface of theslit plate 275. That is, in the embodiment shown in FIG. 33, the secondliquid immersion area LA2 is not formed. Even when the space between theprojection optical system PL and the slit plate 275 is filled with theliquid LQ to substantially improve the numerical aperture NA of theprojection optical system PL by arranging the optical sensor 282 of thelight receiver 290 so that the optical sensor 282 makes contact with theslit plate 275 as described above, the light receiver 290(light-receiving element 282) can satisfactorily receive the light beamwhich has passed through the projection optical system PL.

In the case of the arrangement in which the optical sensor 282 is incontact with the slit plate 275, it is preferable that the slit plate275 (glass plate member 274) is as thin as possible to such an extentthat the slit plate 275 (glass plate member 274) is not warped by theweight of the liquid LQ in the first liquid immersion area LA1. Further,it is also possible to adopt such an arrangement that thelight-receiving surface 282A of the light-receiving sensor 282 isexposed upwardly from the glass plate member 274. On the other hand,when the slit plate 275 (glass plate member 274) is provided on thelight-receiving surface 282A of the optical sensor 282 without exposingthe light-receiving surface 282A, the liquid immersion area LA1 can beformed satisfactorily, because the flat area is increased.

An adhesive can be used to join the optical sensor 282 to the lowersurface of the slit plate 275. In this arrangement, it is desirable thatthe adhesive has a high transmittance with respect to the exposure beam,and the adhesive has such a refractive index that the exposure beam,which is which has passed through the slit section (light-transmittingsection) 271, successfully comes into the light-receiving surface 282Aof the optical sensor 282.

The embodiment shown in FIG. 33 is constructed such that the opticalsensor 282 makes tight contact with the lower surface of the slit plate275. However, a light-receiving element may be formed by the patterningon the lower surface of the slit plate 275 (glass plate member 274).

Fourteenth Embodiment

As described above, when the imaging characteristic of the projectionoptical system PL is measured in the slit scan manner, the light beam isradiated onto the light receiver 290 (optical element 276) through theliquid LQ while moving the slit plate 275 (slit section 271) relative tothe light beam (exposure beam EL) which has passed through theprojection optical system PL. In this case, there is a possibility thatthe following inconvenience arises. That is, the projection opticalsystem PL (optical element 260 disposed at the end portion) may bevibrated through the liquid LQ in the first liquid immersion area LA1between the projection optical system PL and the slit plate 275 duringthe light-receiving operation performed by the light receiver 290 due tothe movement of the slit plate 275. Further, the slit plate 275 may bewarped or fluctuated by the force of the liquid LQ to deteriorate thespatial image measurement accuracy.

Accordingly, in this embodiment, as shown in FIG. 34, through-holes 320are provided at predetermined positions of the slit plate 275. In thisway, even when the slit plate 275 is moved with respect to theprojection optical system PL, the liquid LQ, which is included in thefirst liquid immersion area LA1 between the projection optical system PLand the slit plate 275, can escape to the space SP via the through-holes320. Therefore, even when the slit plate 275 is moved, no differencearises between the pressure of the liquid LQ in the first liquidimmersion area LA1 between the projection optical system PL and the slitplate 275 and the pressure of the liquid LQ in the second liquidimmersion area LA2 between the slit plate 275 and the light receiver 290(optical element 276). Any inconvenience does not arise, which would beotherwise caused such that the slit plate 275 is warped. When the slitplate 275 is moved, the liquid LQ in the first liquid immersion area LA1is also moved in the lateral direction (in the surface direction of theslit plate 275). However, when the liquid LQ is allowed to be movable inthe vertical direction as well by providing the through-holes 320, it ispossible to more appropriately avoid the occurrence of the inconvenienceof the warpage of the slit plate 275 or the like. No large pressurefluctuation of the liquid LQ is caused as well in the first liquidimmersion area LA1 between the projection optical system PL and the slitplate 275, because the liquid LQ is movable between the first liquidimmersion area LA1 and the second liquid immersion area LA2 via thethrough-holes 320. Therefore, it is possible to avoid the occurrence ofthe inconvenience which would be otherwise caused such that theprojection optical system PL is fluctuated (vibrated) due to thepressure fluctuation of the liquid LQ caused by the movement of the slitplate 275.

FIG. 35 shows a plan view illustrating the slit plate 275 shown in FIG.34. As shown in FIG. 35, a plurality of the through-holes 320 areprovided, i.e., the four through-holes 320 are provided in thisembodiment. The plurality of (four) through-holes 320 are provided atthe positions at which the through-holes 320 are opposed to one anotherwith the slit section 271 of the slit plate 275 intervening therebetweenrespectively. The through-holes 320 are provided inside the first liquidimmersion area LA1 of the liquid LQ with which the space between theprojection optical system PL and the slit plate 275 is filled.Accordingly, even when the slit plate 275 is moved, the liquid LQ in thefirst liquid immersion area LA1 can escape to the space SP via thethrough-holes 320. The through-holes 320 are formed so that thethrough-holes 320 are opposed to one another while interposing the slitsection 271 provided at the substantially central portion of the slitplate 275. The through-holes 320 are formed at the positions of pointsymmetry with respect to the center of the slit plate 275 respectively.Therefore, it is possible to maintain the surface accuracy (flatness) ofthe slit plate 275.

The number of the through-holes 320 is not limited to four. An arbitrarynumber of the through-holes 320 may be provided. Alternatively, thenumber of the through-hole 320 may be one. As shown in FIG. 35, thethrough-holes 320 are provided at equal intervals to surround the slitsection 271 in this embodiment. However, the through-holes 320 may beprovided at unequal intervals. Further, the distances between the slitsection 271 (or the center thereof) and the plurality of through-holes320 may be either identical to one another or different from each other.

When the space SP is filled with the liquid LQ in order to form thesecond liquid immersion area LA2 when the through-holes 320 are providedfor the slit plate 275, the following arrangement is also available inaddition to the arrangement in which the liquid supply unit 300 and theliquid recovery unit 304 are used as explained with reference to, forexample, FIG. 25. That is, the liquid supply mechanism 210 may be usedto supply the liquid LQ to the space SP between the slit plate 275 andthe light receiver 290 (optical element 276) via the through-holes 320.Further, the liquid recovery mechanism 220 may be used to recover theliquid LQ from the space SP between the slit plate 275 and the lightreceiver 290 (optical element 276) via the through-holes 320. That is,the second liquid immersion area LA2 may be formed between the slitplate 275 and the light receiver 290 (optical element 276) by using theliquid supply mechanism 210 capable of supplying the liquid LQ to thespace between the projection optical system PL and the substrate Pduring the exposure process and the liquid recovery mechanism 220capable of recovering the liquid LQ from the space between theprojection optical system PL and the substrate P.

When the second liquid immersion area LA2 is formed by using the liquidsupply mechanism 210, the liquid supply mechanism 210 supplies theliquid LQ to the space SP via the through-holes 320 from the supplynozzles 213 as shown in FIG. 36A. The liquid LQ on the slit plate 275(including the liquid LQ allowed to overflow from the space SP via thethrough-holes 320) is recovered from the recovery nozzles 223 of theliquid recovery mechanism 220. Accordingly, as shown in FIG. 36B, thefirst liquid immersion area LA1 and the second liquid immersion area LA2are formed respectively by using the liquid supply mechanism 210 and theliquid recovery mechanism 220.

The light beam (exposure beam EL), which has passed through theprojection optical system PL, is received by the light receiver 290through the liquid LQ and the slit plate 275, and then the liquidrecovery mechanism 220 recovers the liquid LQ from the first liquidimmersion area LA1 on the slit plate 275. After that, the substratestage PST is moved in order to perform the exposure process, and theprojection optical system PL and the substrate P are opposed to oneanother. However, in this situation, the slit plate 275 is retractedfrom the position under the projection optical system PL as shown inFIG. 36C. A lid member 322 is placed on the through-holes 320 of theslit plate 275 having been retracted from the position under theprojection optical system PL. In this embodiment, the lid member 322closes the through-holes 320 by covering the entire slit plate 275therewith. The lid member 322 is placed on the slit plate 275 by an arm322A which constitutes a lid mechanism. The exposure process isperformed for the substrate P in the state in which the through-holes320 are closed by the lid member 322. The substrate stage PST is movedduring the exposure process for the substrate P. However, there is sucha possibility that the liquid LQ in the space SP may be leaked(scattered) to the outside via the through-holes 320 in accordance withthe movement of the substrate stage PST. Accordingly, the through-holes320 are closed by the lid member 322 at least during the exposureprocess for the substrate P, and thus it is possible to avoid theinconvenience which would be otherwise caused such that the liquid LQ inthe space SP leaks to the outside via the through-holes 320. Further, itis also possible to avoid the inconvenience which would be otherwisecaused such that the liquid LQ in the space SP is vaporized to changethe environment in which the exposure apparatus EX is placed. When thelight beam is detected through the liquid LQ by using the light receiver290, then the arm 322A detaches the lid member 322 from the slit plate322, and then the first and second liquid immersion areas LA1, LA2 areformed by using the liquid supply mechanism 210 and the liquid recoverymechanism 220 as shown in FIGS. 36A and 36B. The lid mechanism is notlimited to the form as explained above. For example, the followingarrangement is also available. That is, a lid member is attached by theaid of a hinge section to a predetermined position of the slit plate 275or the projection 283. An actuator is used to open the lid member duringthe measurement process performed by the light receiver 290 and closethe lid member during the exposure process for the substrate P.

Fifteenth Embodiment

As for the holes (communicating passages) for making communicationbetween the outside and the inside of the space SP between the slitplate 275 and the light receiver 290, it is also allowable to formsecond through-holes provided outside the first liquid immersion areaLA1 as shown in FIG. 37, in addition to the through-holes 320 providedfor the slit plate 275. FIG. 37 shows a sectional view illustrating anexample in which the second through-holes 330 are formed, and FIG. 38shows a plan view. With reference to FIGS. 37 and 38, a circumferentialwall 332 is provided around the projection 283 on the upper surface ofthe Z tilt stage 252 so that the projection 283 is surrounded thereby. Alid member 334 is provided on the circumferential wall 332. A bufferspace 336 is formed by the projection 283, the circumferential wall 332,and the lid member 334. The second through-holes 330, which connect thespace SP and the buffer space 336, are formed at predetermined positionsof the walls of the projection 283 and the holding member 285. In thisembodiment, as shown in FIG. 38, a plurality of (eight in thisembodiment) second through-holes 330 are provided at predeterminedintervals around the space SP. The number and the arrangement of thesecond through-hole or through-holes 330 can be arbitrarily established.Owing to the provision of the second through-holes 330, even when theslit plate 275 is moved to change the volume of the first liquidimmersion area AR1, the liquid LQ in the second liquid immersion areaLA2 connected to the first liquid immersion area LA1 via thethrough-holes 320 can escape to the buffer space 330 via the secondthrough-holes 330. Therefore, it is possible to further avoid theinconvenience such as the pressure fluctuation in the first liquidimmersion area LA1.

As shown in FIG. 39, second through-holes 330 may be provided for theslit plate 275 as a modified embodiment of the embodiment shown in FIGS.37 and 38. The second through-holes 330 are provided outside the firstliquid immersion area LA1. FIG. 40 shows a plan view illustrating theslit plate 275 shown in FIG. 39. As shown in FIG. 40, a plurality of(eight in this embodiment) second through-holes 330 are provided. Theplurality of (eight) second through-holes 330 are provided at positionsat which the second through-holes 330 are opposed to one another withthe slit section 271 of the slit plate 275 intervening therebetweenrespectively. Accordingly, when the liquid LQ in the first liquidimmersion area LA1 escapes to the space SP via the through-holes 320when the slit plate 275 is moved, the liquid LQ in the space SP canescape to the outside via the second through-holes 330.

When the liquid LQ overflows from the second through-holes 330 formedfor the slit section 275, the liquid LQ outflows to the outside of theslit plate 275 (projection 283). However, a recovery mechanism 304,which recovers the liquid LQ allowed to outflow from the secondthrough-holes 330, is provided around the projection 283 provided withthe slit plate 275 on the Z tilt stage 252. The recovery mechanism 340comprises a groove 341 which is provided around the projection 283 onthe Z tilt stage 252, a porous member 342 which is arranged in thegroove 341 and which is composed of a porous ceramics or a sponge-likemember capable of retaining the liquid LQ, a tank 344 which serves as aliquid-accommodating section connected to the groove 341 via a flowpassage 343, and a vacuum system 345 which is composed of a vacuum pumpor the like connected to the tank 344 via a flow passage 346. The flowpassage 346 is provided with a valve 346A which opens/closes the flowpassage 346. A discharge flow passage 344A is connected to the tank 344.The liquid LQ, which outflows to the surrounding of the projection 283from the second through-holes 330, is retained by the porous member 342arranged in the groove 341. The recovery mechanism 340 recovers theliquid LQ in the groove 341 (porous member 342) so that the liquid LQ issucked together with the surrounding gas by driving the vacuum system345 in a state in which the flow passage 346 is open by operating thevalve 346A. The recovered liquid LQ is collected in the tank 344. Whenthe liquid LQ is pooled in the tank 344, the liquid LQ is dischargedfrom the discharge flow passage 344A. In this situation, the liquid LQis collected at the lower portion of the tank 344. Therefore, the liquidLQ does not flow into the vacuum system 345. In other words, the liquidLQ recovered from the groove 341 and the surrounding gas are subjectedto the gas/liquid separation in the tank 344. Owing to the provision ofthe recovery mechanism 340, it is possible to avoid the inconveniencewhich would be otherwise caused such that the liquid LQ, which isallowed to outflow from the second through-holes 330 and the firstliquid immersion area LA1, remains on the Z tilt stage 252.

A variable mechanism, which changes the size of the through-hole 320,may be provided for the through-hole 320 (or the second through-hole330). For example, when the through-holes 320 (or the secondthrough-holes 330) are increased in size during the measurement of thespatial image, then it is possible to lower the viscous resistance ofthe liquid LQ when the liquid LQ passes through the through-holes 320,and the liquid LQ can be moved smoothly. When the through-holes 320 areincreased in size, the liquid LQ is easily poured into the space SP viathe through-holes 320 as explained with reference to FIG. 36. When theoperation other than the measurement of the spatial image is performed(specifically during the exposure operation), the variable mechanism isused to decrease the through-holes 320 (or the second through-holes 330)in size or close the through-holes 320 (or the second through-holes330). Accordingly, it is possible to avoid the occurrence of theinconvenience which would be otherwise caused such that the liquid LQ inthe space SP is vaporized to change the environment in which theexposure apparatus EX is placed and/or the liquid LQ outflows to theoutside of the space SP in accordance with the movement of the substratestage PST.

Sixteenth Embodiment

The respective embodiments of the eleventh to fifteenth embodimentsdescribed above are constructed such that the first liquid immersionarea LA1 is locally formed in a part of the area on the slit plate 275.However, as shown in FIG. 41, the entire slit plate 275 may be immersedin the liquid LQ. With reference to FIG. 41, a gutter member 350 isprovided on the Z tilt stage 252. The slit plate 275 is supported by asupport member 351 attached onto the bottom section 350B of the guttermember 350. An optical element 276, which is retained by a holdingmember 285, is arranged under the slit plate 275 (on the downstream sideof the optical path). The holding member 285 is also attached to thebottom section 350E of the gutter member 350. Second through-holes 330,which make communication between the outside and the inside of the spaceSP between the slit plate 275 and the optical element 276, are providedfor the support member 351. The upper end of the opening 350A of thegutter member 350 is disposed at the position higher than those of theslit plate 275, the supply ports 213A of the liquid supply nozzles 213,and the recovery ports 223A of the liquid recovery nozzles 223.

When the first liquid immersion area LA1 and the second liquid immersionarea LA2 are formed, then the projection optical system PL is opposed tothe slit plate 275 disposed in the gutter member 350, and then theliquid supply mechanism 210 is driven to supply the liquid LQ into thegutter member 350 from the supply nozzles 213. The space between theslit plate 275 and the optical element 260 disposed at the end portionof the projection optical system PL is filled with the liquid LQsupplied into the gutter member 350 to form the first liquid immersionarea LA1. Further, the liquid LQ passes through the through-holes 320and the second through-holes 330, and the space SP between the slitplate 275 and the optical element 276 is filled with the liquid LQ toform the second liquid immersion area LA2. Concurrently therewith, theliquid recovery mechanism 220 is driven to recover the liquid LQcontained in the gutter member 350 from the recovery nozzles 223.Accordingly, the interior of the gutter member 350 is filled with apredetermined amount of the liquid LQ.

The eleventh to sixteenth embodiments described above have beenexplained as exemplified by the case in which the optical member (slitplate) 275 and the light receiver 290 are applied to the spatialimage-measuring unit 270 for measuring the imaging characteristic of theprojection optical system PL. However, as shown in FIG. 42, thoseprovided on the substrate stage PST other than the spatialimage-measuring unit 270 also include, for example, a dose sensor(illuminance sensor) 360 which measures the information about theradiation amount of the light beam which has passed through theprojection optical system PL and which is disclosed, for example, inJapanese Patent Application Laid-open No. 11-16816 (corresponding toUnited States Patent Publication No. 2002/0061469), and an irradiationirregularity sensor 370 which is disclosed, for example, in JapanesePatent Application Laid-open No. 57-117238 (corresponding to U.S. Pat.No. 4,465,368) and U.S. Pat. No. 6,002,467. The present invention isalso applicable to the dose sensor 360 and the irradiation irregularitysensor 370 as described above. The disclosures of the patent documentsare incorporated herein by reference within a range of permission of thedomestic laws and ordinances of the state designated or selected in thisinternational application.

FIG. 43 schematically shows the dose sensor 360. The dose sensor 360measures the radiation amount (illuminance) of the exposure beamradiated onto the image plane side of the projection optical system PL.The dose sensor 360 comprises an upper plate 363 which is provided onthe Z tilt stage 252, and an optical sensor 364 which receives the lightbeam which has passed through the upper plate 363. The upper plate 363includes a glass plate member 362, and a light transmissionamount-adjusting film 361 which is provided on the upper surface of theglass plate member 362. The light transmission amount-adjusting film 361is composed of, for example, a chromium film. The light transmissionamount-adjusting film 361 has a predetermined light transmittance, whichis provided on the entire upper surface region of the glass plate member362. The light amount, which has come into the optical sensor 364, isreduced by providing the light transmission amount-adjusting film 361.Accordingly, the inconvenience such as the saturation and the damage onthe optical sensor 364 is avoided, which would be otherwise caused bythe radiation of the light beam in an excessive light amount. The dosesensor 360 is used to perform the measuring operation at a predeterminedtiming, for example, when the mask M is exchanged.

When the radiation amount of the exposure beam EL which has passedthrough the projection optical system PL is measured by using the dosesensor 360, then the liquid LQ is supplied to the space between theprojection optical system PL and the upper plate 363 to form the firstliquid immersion area LA1 in a state in which the projection opticalsystem PL and the upper plate 363 are opposed to one another in the samemanner as in the embodiment described above, and the liquid LQ issupplied to the space between the upper plate 363 and the optical sensor364 to form the second liquid immersion area LA2. The exposure beam ELis radiated onto the upper plate 363 via the projection optical systemPL and the liquid LQ in the first liquid immersion area LA1. An opticalsystem (optical element) may be arranged between the upper plate 363 andthe optical sensor 364. In this arrangement, the second liquid immersionarea LA2 is formed between the upper plate 363 and the optical elementarranged at the position nearest to the upper plate 363. The opticalsensor 364 may be in tight contact with the upper plate 363.

The arrangement, in which the second liquid immersion area LA2 isprovided for the dose sensor as explained in this embodiment, may beapplied to the dose sensors described in the sixth to eighthembodiments.

FIG. 44 schematically shows the irradiation irregularity sensor 370. Theirradiation irregularity sensor 370 measures, at a plurality ofpositions, the illuminance (intensity) of the exposure beam radiatedonto the image plane side via the projection optical system PL tomeasure the uneven illuminance (illuminance distribution) of theexposure beam radiated onto the image plane side of the projectionoptical system PL. The irradiation irregularity sensor 370 comprises anupper plate 374 which is provided on the Z tilt stage 252, and anoptical sensor 375 which receives the light beam which has passedthrough a pinhole section 371 provided for the upper plate 374. Theupper plate 374 has a thin film 372 which is provided on the surface ofa glass plate member 373 and which contains a light-shielding materialsuch as chromium. The thin film 372 is subjected to the patterning toprovide the pinhole section 371 at a central portion thereof.

When the illuminance distribution is measured by using the irradiationirregularity sensor 370, then the space between the projection opticalsystem PL and the upper plate 374 is filled with the liquid LQ in astate in which the projection optical system PL and the upper plate 374of the irradiation irregularity sensor 370 are opposed to one another,and the space between the upper plate 374 and the optical sensor 375 isalso filled with the liquid LQ. The pinhole section 371 is successivelymoved at a plurality of positions in the radiation area (projectionarea) onto which the exposure beam EL is radiated. An optical system(optical element) may be arranged between the upper plate 374 and theoptical sensor 375. In this arrangement, the second liquid immersionarea LA2 is formed between the upper plate 374 and the optical elementarranged at the position nearest to the upper plate 374. The upper plate374 and the optical sensor 375 may be in tight contact with each other.

The arrangement, in which the second liquid immersion area LA2 isprovided for the irradiation irregularity sensor as explained in thisembodiment, may be applied to the irradiation irregularity sensorsdescribed in the second to fifth embodiments and the ninth and tenthembodiments. The structure, which is adopted for the sensor of each ofthe first to tenth embodiments, may be adopted for the spatialimage-measuring unit explained in each of the eleventh to sixteenthembodiments, in place of or in addition to the internal structure of thespatial image-measuring unit explained in each of the eleventh tosixteenth embodiments. Further, the structure, which is explained in theembodiment described above, may be adopted for any one of the spatialimage-measuring unit 270, the dose sensor 360, and the irradiationirregularity sensor 370 shown in FIG. 42. Further, the structureexplained in the embodiment described above may be adopted for any twoor all of them.

The present invention is also applicable to a sensor which is detachablewith respect to the substrate stage PST (z stage 51) as disclosed, forexample, in Japanese Patent Application Laid-open Nos. 11-238680 and2000-97616 and United States Patent Publication No. 2004/0090606. Thepresent invention is also applicable to a sensor for measuring thewavefront aberration as disclosed in U.S. Pat. No. 6,650,399. Thedisclosures of the patent documents are incorporated herein by referencewithin a range of permission of the domestic laws and ordinances of thestate designated or selected in this international application.

In each of the eleventh to sixteenth embodiments described above, theshape of the nozzle is not specifically limited. For example, two pairsof nozzles may be used to supply or recover the liquid LQ for the longside of the projection area AR1. In this arrangement, the supply nozzlesand the recovery nozzles may be arranged and aligned vertically in orderto successfully supply and recover the liquid LQ in any one of thedirections of the +X direction and the −X direction. That is, it ispossible to adopt various forms which make it possible to continuouslyfill the space between the substrate P and the optical element 260 ofthe projection optical system PL with a sufficient amount of the liquidLQ. It is not necessarily indispensable that the supply position and/orthe recovery position of the liquid LQ is changed depending on thedirection of movement of the substrate P. The supply and the recovery ofthe liquid LQ may be continued from any predetermined position.

In each of the embodiments of the present invention, pure water is usedas the liquid LQ, because the ArF excimer laser light source is used asthe light source 1. Pure water is advantageous in that pure water isavailable in a large amount with ease, for example, in the semiconductorproduction factory, and pure water exerts no harmful influence, forexample, on the optical element (lens) and the photoresist on the waferW (substrate P). Further, pure water exerts no harmful influence on theenvironment, and the content of impurity is extremely low. Therefore, itis also expected to obtain the function to wash the surface of the waferW (substrate 9) and the surface of the optical element provided at theend surface of the projection optical system PL. It is also consideredthat pure water of the factory may have a low level (purity or degree ofpure water). Therefore, in such a situation, the exposure apparatusitself may posses an ultrapure water-producing mechanism.

It is approved that the refractive index n of pure water (water) withrespect to the exposure beam having a wavelength of about 193 nm isapproximately in an extent of 1.44. When the ArF excimer laser beam(wavelength: 193 nm) is used as the light source of the exposure beam,then the wavelength is shortened on the wafer W (substrate 9) by 1/n,i.e., to about 134 nm, and a high resolution is obtained. Further, thedepth of focus is magnified about n times, i.e., about 1.44 times ascompared with the value obtained in the air. Therefore, when it isenough to secure an approximately equivalent depth of focus as comparedwith the case of the use in the air, it is possible to further increasethe numerical aperture of the projection optical system PL. Also in thisviewpoint, the resolution is improved.

It is also possible to use the KrF excimer laser light source and the F₂laser light source as the light source 1 to be used for the liquidimmersion exposure. When the F₂ laser light source is used, it ispreferable to use a fluorine-based liquid including, for example,fluorine-based oil and perfluoropolyether (PFPE) through which the F₂laser beam is transmissive, as the liquid for the liquid immersionexposure (including the liquid to be used for the second liquidimmersion area). Alternatively, other than the above, it is alsopossible to use those (for example, cedar oil) which have thetransmittance with respect to the exposure beam, which have therefractive index as high as possible, and which are stable against thephotoresist subjected to the coating for the surface of the wafer W(substrate P) and the projection optical system PL. As described above,the liquid to be used for the first liquid immersion area and the liquidto be used for the second liquid immersion area may be separately useddepending on the purpose.

The exposure apparatus, to which the liquid immersion method is appliedas described above, is constructed such that the optical path space,which is disposed on the outgoing side of the terminal end opticalmember of the projection optical system PL, is filled with the liquid(pure water) to expose the wafer W (substrate P). However, as disclosedin International Publication No. 2004/019128, the optical path space,which is disposed on the incoming side of the terminal end opticalmember of the projection optical system, may be also filled with theliquid (pure water). In this arrangement, even when the projectionoptical system PL has a large numerical aperture of not less than 1.0, aparallel flat plate having no refractive force or a lens having anextremely small refractive force can be adopted as the terminal endoptical member.

When the liquid immersion method is used, the numerical aperture NA ofthe projection optical system is 0.9 to 1.7 in some cases. When thenumerical aperture NA of the projection optical system is large asdescribed above, it is desirable to use the polarized illumination,because the imaging characteristic is deteriorated due to thepolarization effect in some cases with the random polarized light whichhas been hitherto used as the exposure beam. In this case, it isappropriate that the linear polarized illumination, which is adjusted tothe longitudinal direction of the line pattern of the line-and-spacepattern of the mask (reticle), is effected so that the diffracted lightof the S-polarized light component (component in the polarizationdirection along with the longitudinal direction of the line pattern) isdominantly allowed to outgo from the pattern of the mask (reticle).

When the space between the projection optical system and the resistcoating the substrate surface is filled with the liquid, the diffractedlight of the S-polarized light component, which contributes to theimprovement in the contrast, has the high transmittance on the resistsurface, as compared with the case in which the space between theprojection optical system and the resist coating the substrate surfaceis filled with the air (gas). Therefore, it is possible to obtain thehigh imaging performance even when the numerical aperture NA of theprojection optical system exceeds 1.0. Further, it is more effective toappropriately combine, for example, the phase shift mask and the obliqueincidence illumination method (especially the dipole illuminationmethod) adjusted to the longitudinal direction of the line pattern asdisclosed in Japanese Patent Application Laid-open No. 6-188169.

It is also effective to use the combination of the oblique incidenceillumination method and the polarized illumination method in which thelinear polarization is effected in the tangential (circumferential)direction of the circle having the center of the optical axis asdisclosed in Japanese Patent Application Laid-open No. 6-53120, withoutbeing limited to only the linear polarized illumination (S-polarizedillumination) adjusted to the longitudinal direction of the line patternof the mask (reticle). In particular, when the pattern of the mask(reticle) includes not only the line pattern extending in onepredetermined direction, but the pattern also includes the line patternsextending in a plurality of different directions in a mixed manner, thenit is possible to obtain the high imaging performance even when thenumerical aperture NA of the projection optical system is large, byusing, in combination, the zonal illumination method and the polarizedillumination method in which the light is linearly polarized in thetangential direction of the circle having the center of the opticalaxis, as disclosed in Japanese Patent Application Laid-open No. 6-53120as well.

In the embodiments described above, the exposure apparatus is adopted,in which the space between the projection optical system PL and thewafer W (substrate P) is locally filled with the liquid. However, thepresent invention is also applicable to a liquid immersion exposureapparatus in which a stage retaining a substrate as an exposureobjective is moved in a liquid tank, and a liquid immersion exposureapparatus in which a liquid tank having a predetermined depth is formedon a stage and a substrate is retained therein. The structure and theexposure operation of the liquid immersion exposure apparatus in whichthe stage retaining the substrate as the exposure objective is moved inthe liquid tank are described in detail, for example, in Japanese PatentApplication Laid-open No. 6-124873. The structure and the exposureoperation of the liquid immersion exposure apparatus in which the liquidtank having the predetermined depth is formed on the stage and thesubstrate is retained therein are described in detail, for example, inJapanese Patent Application Laid-open No. 10-303114 and U.S. Pat. No.5,825,043. The contents of the descriptions in these literatures areincorporated herein by reference respectively within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

The present invention is also applicable to a twin-stage type exposureapparatus which is provided with two stages capable of movingindependently in the XY direction while separately placing processingobjective substrates such as wafers. The structure and the exposureoperation of the twin-stage type exposure apparatus are disclosed, forexample, in Japanese Patent Application Laid-open Nos. 10-163099 and10-214783 (corresponding to U.S. Pat. Nos. 6,341,007, 6,400,441,6,549,269, and 6,590,634), Japanese Patent Application Laid-open No.2000-505958 (PCT) (corresponding to U.S. Pat. No. 5,969,441), and U.S.Pat. No. 6,208,407. The disclosures thereof are incorporated herein byreference within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

As disclosed in Japanese Patent Application Laid-open No. 11-135400, thepresent invention is also applicable to the exposure apparatus which isprovided with an exposure stage that is movable while retaining aprocessing objective substrate such as a wafer, and a measuring stagethat is provided with, for example, various measuring members andsensors. In this case, at least a part of the plurality of sensors(measuring units) explained in each of the first to sixteenthembodiments can be provided on the measuring stage.

The embodiments described above have been explained as exemplified bythe case in which the ArF excimer laser light source is used as theexposure light source 1. However, other than the above, those usable asthe exposure light source 1 include, for example, the ultra-high voltagemercury lamp for irradiating the g-ray (wavelength: 436 nm) or the i-ray(wavelength: 365 nm), the KrF excimer laser (wavelength: 248 nm), the F₂laser (wavelength: 157 nm), the Kr₂ laser (wavelength: 146 nm), the highfrequency-generating unit for the YAG laser, and the highfrequency-generating unit for the semiconductor laser.

Further, it is also allowable to use, as the light source, the highharmonic wave obtained by amplifying the single wavelength laser beam inthe infrared region or the visible region emitted from the DFBsemiconductor laser or the fiber laser with the fiber amplifier doped,for example, with erbium (or both of erbium and ytterbium) and effectingthe wavelength conversion into the ultraviolet light beam by using thenonlinear optical crystal. For example, assuming that the emissionwavelength of the single wavelength laser is within a range of 1.51 to1.59 those outputted include the 8-fold high harmonic wave having thegenerated wavelength within a range of 189 to 199 nm and the 10-foldhigh harmonic wave having the generated wavelength within a range of 151to 159 nm.

Further, assuming that the emission wavelength is within a range of 1.03to 1.12 μm, the 7-fold high harmonic wave having the generatedwavelength within a range of 147 to 160 nm is outputted. In particular,assuming that the emission wavelength is within a range of 1.099 to1.106 μm, the 7-fold high harmonic wave having the generated wavelengthwithin a range of 157 to 158 nm, i.e., the ultraviolet light beam havingapproximately the same wavelength as that of the F₂ laser beam isobtained. In this case, for example, the ytterbium-doped fiber laser canbe used as the single wavelength emission laser.

The embodiments described above have been explained as exemplified bythe case in which fluorite (calcium fluoride: CaF₂) is used, forexample, as the material for the optical element provided in theillumination optical system IS, the material for the refractive memberfor constructing the projection optical system PL, and the material forthe plano-convex lens 41, 45, 52, 57, 62, 71. However, these materialsare selected from fluoride crystals such as magnesium fluoride (MgF₂) ormixed crystals thereof, and optical materials such as quartz glass dopedwith a substance such as fluorine or hydrogen through which the vacuumultraviolet light is transmissive, depending on the wavelength of theexposure beam. As for the quartz glass doped with the predeterminedsubstance, the transmittance is lowered when the wavelength of theexposure beam is shorter than about 150 nm. Therefore, when the vacuumultraviolet light beam having the wavelength of not more than about 150nm is used as the exposure beam, the fluoride crystal such as fluorite(calcium fluoride) or magnesium fluoride or the mixed crystal thereof isused as the optical material for the optical element.

The first to tenth embodiments have been explained as exemplified by theexposure apparatus based on the step-and-repeat system. Further, theeleventh to sixteenth embodiments have been explained as exemplified bythe exposure apparatus based on the step-and-scan system. However, thepresent invention is also applicable to the exposure apparatus based onany one of the systems. Further, the present invention is alsoapplicable to the exposure apparatus based on the step-and-stitch systemin which at least two patterns are partially overlaid and transferred onthe substrate (wafer). Further, the present invention is not limited tothe exposure apparatus to be used for producing the semiconductorelement. The present invention is also applicable, for example, to theexposure apparatus which is used for producing the display including,for example, the liquid crystal display device (LCD) and which transfersthe device pattern onto the glass plate, the exposure apparatus which isused for producing the thin film magnetic head and which transfers thedevice pattern onto the ceramic wafer, and the exposure apparatus whichis used for producing the image pickup device such as CCD. Further, thepresent invention is also applicable to the exposure apparatus whichtransfers the circuit pattern, for example, to the glass substrate orthe silicon wafer in order to produce the reticle or the mask to beused, for example, for the optical exposure apparatus, the EUV exposureapparatus, the X-ray exposure apparatus, and the electron beam exposureapparatus. In general, the transmissive type reticle is used for theexposure apparatus which employs, for example, the DUV (far ultraviolet)light beam or the VUV (vacuum ultraviolet) light beam. For example,quartz glass, quartz glass doped with fluorine, fluorite, magnesiumfluoride, or quartz crystal is used as the reticle substrate. Thetransmissive type mask (stencil mask, membrane mask) is used, forexample, for the electron beam exposure apparatus or the X-ray exposureapparatus based on the proximity system. For example, the silicon waferis used as the mask substrate. The exposure apparatuses as describedabove are disclosed, for example, in WO 99/34255, WO 99/50712, WO99/66370, and Japanese Patent Application Laid-open Nos. 11-194479,2000-12453, and 2000-29202.

The substrate P, which is usable in the respective embodiments describedabove, is not limited to the semiconductor wafer for producing thesemiconductor device. Those applicable include, for example, the glasssubstrate for the display device, the ceramic wafer for the thin filmmagnetic head, and the master plate (synthetic quartz, silicon wafer)for the mask or the reticle to be used for the exposure apparatus.

When the linear motor is used for the substrate stage PST (wafer stage15) and/or the mask stage MST (reticle stage 13), it is allowable to useany one of those of the air floating type based on the use of the airbearing and those of the magnetic floating type based on the use of theLorentz's force or the reactance force. Each of the stages PST (15), MST(13) may be either of the type in which the movement is effected alongthe guide or of the guideless type in which no guide is provided. Anexample of the use of the linear motor for the stage is disclosed inU.S. Pat. Nos. 5,623,853 and 5,528,118. The contents of the descriptionsin the literatures are incorporated herein by reference respectivelywithin a range of permission of the domestic laws and ordinances of thestate designated or selected in this international application.

As for the driving mechanism for each of the stages PST (15), MST (13),it is also allowable to use a plane motor in which a magnet unitprovided with two-dimensionally arranged magnets and an armature unitprovided with two-dimensionally arranged coils are opposed to oneanother, and each of the stages PST (15), MST (13) is driven by theelectromagnetic force. In this arrangement, any one of the magnet unitand the armature unit is connected to the stage PST (15), MST (13), andthe other of the magnet unit and the armature unit is provided on theside of the movable surface of the stage PST (15), MST (13).

The reaction force, which is generated in accordance with the movementof the substrate stage PST (wafer stage 15), may be mechanicallyreleased to the floor (ground) by using a frame member so that thereaction force is not transmitted to the projection optical system PL.The method for handling the reaction force is disclosed in detail, forexample, in U.S. Pat. No. 5,528,118 (Japanese Patent ApplicationLaid-open No. 8-166475). The contents of the descriptions in theliteratures are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

The reaction force, which is generated in accordance with the movementof the mask stage MST (reticle stage 13), may be mechanically releasedto the floor (ground) by using a frame member so that the reaction forceis not transmitted to the projection optical system PL. The method forhandling the reaction force is disclosed in detail, for example, in U.S.Pat. No. 5,874,820 (Japanese Patent Application Laid-open No. 8-330224).The disclosures in the literatures are incorporated herein by referencewithin a range of permission of the domestic laws and ordinances of thestate designated or selected in this international application.

The exposure apparatus EX according to each of the embodiments describedabove is produced by assembling the various subsystems including therespective constitutive elements as defined in claims so that thepredetermined mechanical accuracy, the electric accuracy, and theoptical accuracy are maintained. In order to secure the variousaccuracies, those performed before and after the assembling include theadjustment for achieving the optical accuracy for the various opticalsystems, the adjustment for achieving the mechanical accuracy for thevarious mechanical systems, and the adjustment for achieving theelectric accuracy for the various electric systems. The steps ofassembling the various subsystems into the exposure apparatus include,for example, the mechanical connection, the wiring connection of theelectric circuits, and the piping connection of the air pressurecircuits in correlation with the various subsystems. It goes withoutsaying that the steps of assembling the respective individual subsystemsare performed before performing the steps of assembling the varioussubsystems into the exposure apparatus. When the steps of assembling thevarious subsystems into the exposure apparatus are completed, theoverall adjustment is performed to secure the various accuracies as theentire exposure apparatus. It is desirable that the exposure apparatusis produced in a clean room in which, for example, the temperature andthe cleanness are managed.

Next, an explanation will be made about an embodiment of the method forproducing the microdevice in which the exposure apparatus and theexposure method according to the embodiment of the present invention areused in the lithography step. FIG. 18 shows a flow chart illustratingexemplary steps of producing the microdevice (for example, semiconductorchip such as IC and LSI, liquid crystal panel, CCD, thin film magnetichead, and micromachine). At first, as shown in FIG. 18, the function andthe performance of the microdevice are designed (for example, thecircuit of the semiconductor device is designed) to perform the patterndesign in order to realize the function in the step S20 (designingstep). Subsequently, the mask (reticle), on which the designed circuitpattern is formed, is manufactured in the step S21 (mask productionstep). On the other hand, the wafer is produced by using a material suchas silicon in the step S22 (wafer production step).

Subsequently, the mask and the wafer, which are prepared in the stepsS20 to S22, are used in the step S23 (wafer processing step) to form,for example, the actual circuit on the wafer, for example, by thelithography technique as described later on. Subsequently, the wafer,which is processed in the step S23, is used to assemble the device inthe step S24 (device assembling step). The step S24 includes, forexample, the dicing step, the bonding step, and the packaging step (chipsealing), if necessary. Finally, the inspection, which includes, forexample, the test for confirming the operation and the durability testfor the microdevice manufactured in the step S24, is performed in thestep S25 (inspection step). After performing the steps as describedabove, the microdevice is completed, which is shipped.

FIG. 19 shows an example of the detailed flow of the step S23 shown inFIG. 18 in the case of the semiconductor device. With reference to FIG.19, the surface of the wafer is oxidized in the step S31 (oxidationstep). In the step S32 (CVD step), an insulating film is formed on thewafer surface. In the step S33 (electrode formation step), an electrodeis formed on the wafer by the vapor deposition. In the step S34 (ionimplantation step), an ion is implanted into the wafer. Each of thesteps S31 to S34 described above constitutes the pretreatment step ateach stage of the wafer processing, which is selected and executeddepending on the process required for each stage.

When the pretreatment step is completed at each stage of the waferprocess, the aftertreatment step is executed as follows. At first, inthe aftertreatment step, the wafer is coated with a photosensitive agentin the step S35 (resist formation step). Subsequently, the circuitpattern of the mask is transferred to the wafer in accordance with thelithography system (exposure apparatus) and the exposure methodexplained above in the step S36 (exposure step). Subsequently, theexposed wafer is developed in the step S37 (development step). Theexposed member of the portion other than the portion at which the resistremains is removed by the etching in the step S38 (etching step). Theresist, which is unnecessary after the completion of the etching, isremoved in the step S39 (resist removal step). The circuit patterns areformed in a multiple form on the wafer by repeatedly performing thepretreatment step and the aftertreatment step as described above.

According to the present invention, the exposure beam, which has passedthrough the projection optical system for the liquid immersion havingthe expected performance owing to the supply of the liquid to the imageplane side, is received in the state in which the liquid is not suppliedto the image plane side of the projection optical system. Therefore, themeasurement can be performed accurately without being affected by thestate of water.

The exposure beam, which has passed through the projection opticalsystem, can be received even in the state in which the liquid is absent,for example, by adjusting (decreasing) the angle of the exposure lightflux come into the end surface of the projection optical system (angleformed by the outermost ray and the optical axis).

According to the present invention, the light beam, which is included inthe exposure beam come from the projection optical system and which istransmitted through the light-transmitting section, is allowed to comeinto the light-collecting member and collected without passing throughthe gas. Therefore, even when the exposure beam, which has the largeincident angle due to the increase in the numerical aperture of theprojection optical system, comes into the light-transmitting section, itis possible to reliably receive the exposure beam which has passedthrough the light-transmitting section.

According to the present invention, the exposure beam from theprojection optical system has come into the plate-shaped member throughthe liquid, and the light beam, which is included in the light beam comeinto the plate-shaped member and which is transmitted through thelight-transmitting section, is received. The light-transmitting sectionis formed on the other surface which is not opposed to the projectionoptical system. Therefore, one surface, which is opposed to theprojection optical system, can be made flat. It is possible to avoid,for example, the adhesion of the bubble to one surface of theplate-shaped member and the disturbance of the liquid between theprojection optical system and the plate-shaped member. Further, noaperture (hole) is provided as the light-transmitting section for theplate-shaped member. Therefore, it is possible to avoid the invasion ofthe liquid as well.

According to the present invention, the pattern of the mask istransferred onto the substrate by the exposure under the conditionoptimized depending on the measurement result. Thus, it is possible toaccurately transfer, onto the substrate, the minute pattern formed onthe mask. As a result, it is possible to produce the highly integrateddevice at a high yield.

According to the present invention, the light beam, which is included inthe exposure beam which has passed through the projection optical systemand the liquid and which is transmitted through the light-transmittingsection, comes into the light receiver while being guided by the opticalsystem provided for the measuring means so that the light beam does notpass through the gas. Therefore, even when the exposure beam, which hasthe large incident angle due to the increase in the numerical apertureof the projection optical system, comes into the light-transmittingsection, it is possible to reliably receive the exposure beamtransmitted through the light-transmitting section.

According to the present invention, the light beam, which has passedthrough the projection optical system, can be satisfactorily received bythe light receiver. Therefore, the exposure process can be performedaccurately in the state in which the optimum exposure condition isestablished on the basis of the light-receiving result.

What is claimed is:
 1. An exposure apparatus that is configured toirradiate a substrate with light via a projection optical system and viaa liquid, the exposure apparatus comprising: a stage that is configuredto move relative to the projection optical system; an optical memberthat is provided on the stage and that comprises a first surface and asecond surface, the first surface being arranged to come into contactwith the liquid in a state of being moved to a position facing theprojection optical system, the second surface being arranged to comeinto contact with a gas and to transmit light, having come from theprojection optical system via the liquid and the first surface; and alight-receiving element that comprises a light-receiving surface,wherein the optical member is configured such that at least alarge-angle ray of the light is able to travel from the projectionoptical system to the second surface without passing through any gas,the large-angle ray being defined as a ray of the light having an anglewith an optical axis of the projection optical system sufficiently largeso as to undergo total reflection at an end surface of the projectionoptical system when the liquid is absent, the second surface isconfigured to transmit at least the large-angle ray, and thelight-receiving surface is arranged to receive at least the large-angleray.
 2. The exposure apparatus according to claim 1, wherein the secondsurface is arranged to collect at least the large-angle ray into thelight-receiving surface.
 3. The exposure apparatus according to claim 1,wherein the optical member and the light-receiving surface are disposedapart from each other.
 4. The exposure apparatus according to claim 1,wherein the second surface is arranged to transmit an outermost ray ofthe light.
 5. The exposure apparatus according to claim 1, wherein theoptical member is provided on the stage so that the first surface issubstantially flush with an upper surface of the stage.
 6. The exposureapparatus according to claim 1, further comprising: a holding memberarranged to hold the optical member and attached to the stage so thatthe first surface of the optical member is substantially flush with anupper surface of the stage.
 7. The exposure apparatus according to claim6, wherein the optical member is held by the holding member so that thefirst surface is substantially flush with an upper surface of theholding member.
 8. The exposure apparatus according to claim 6, whereinthe holding member is attached to the stage so that an upper surface ofthe holding member is substantially flush with the upper surface of thestage.
 9. The exposure apparatus according to claim 6, wherein thelight-receiving surface of the light-receiving element is providedinside the holding member.
 10. The exposure apparatus according to claim6, wherein at least part of the optical member is provided inside anopening that is formed on an upper surface of the holding member. 11.The exposure apparatus according to claim 1, wherein at least part ofthe optical member is provided inside an opening that is formed on anupper surface of the stage.
 12. The exposure apparatus according toclaim 1, wherein the stage is configured to move in a state of holdingthe substrate.
 13. The exposure apparatus according to claim 12, whereinthe stage comprises a holder arranged to hold the substrate, and theholder is arranged to hold the substrate so that an upper surface of thestage is substantially flush with an upper surface of the substrate. 14.The exposure apparatus according to claim 1, wherein no gas is disposedin an optical path of the light between the first surface and the secondsurface.
 15. The exposure apparatus according to claim 1, wherein theoptical member comprises a first optical member having the first surfaceand a second optical member having the second surface.
 16. The exposureapparatus according to claim 15, wherein the first optical member andthe second optical member are provided so that no gas is disposed in anoptical path of the light between the first surface and the secondsurface.
 17. The exposure apparatus according to claim 15, wherein thefirst optical member and the second optical member are joined with nogas therebetween.
 18. The exposure apparatus according to claim 1,wherein the second surface comprises a surface which has convex portionsprojecting toward the gas side.
 19. The exposure apparatus according toclaim 1, wherein the second surface is formed into a convex shape towardthe gas side.
 20. The exposure apparatus according to claim 1, whereinthe optical member comprises a reflective surface arranged to reflectlight which has entered from the first surface, toward the secondsurface.
 21. The exposure apparatus according to claim 1, wherein theoptical member comprises a columnar member having a circumferentialsurface arranged to reflect light which has entered from the firstsurface, toward the second surface.
 22. The exposure apparatus accordingto claim 21, wherein a metal film is provided on the circumferentialsurface of the columnar member.
 23. The exposure apparatus according toclaim 1, wherein the optical member comprises a condensing member thatcomprises the second surface and that is arranged to condense the light,which has entered from the first surface.
 24. The exposure apparatusaccording to claim 23, wherein the condensing member comprises at leastone of a plane-convex lens, a diffraction optical element, a lens array,a Fresnel lens, and a reflecting mirror.
 25. The exposure apparatusaccording to claim 1, wherein the optical member comprises a diffractionoptical element that comprises the second surface and that is arrangedto diffract the light which has entered from the first surface.
 26. Theexposure apparatus according to claim 25, wherein the diffractionoptical element is configured such that a diffraction angle with respectto a light beam of light which enters onto the first surface with afirst incident angle is smaller than a diffraction angle with respect toa light beam of light which enters onto the first surface with a secondincident angle greater than the first incident angle.
 27. The exposureapparatus according to claim 1, wherein the optical member comprises adiffusing element that comprises the second surface and that is arrangedto diffuse the light which has entered from the first surface.
 28. Theexposure apparatus according to claim 1, further comprising: at leastone optical element that is arranged to guide the light which has exitedfrom the second surface, toward the light-receiving surface.
 29. Theexposure apparatus according to claim 28, wherein the at least oneoptical element is arranged to convert the light which has exited fromthe second surface into substantially parallel light.
 30. The exposureapparatus according to claim 1, further comprising a light shieldingpart that is arranged to shield the light, the light shielding partbeing provided around the first surface of the optical element.
 31. Theexposure apparatus according to claim 30, wherein the light shieldingpart provides a pinhole in which the first surface is disposed.
 32. Theexposure apparatus according to claim 1, further comprising a lightshielding part that is arranged to shield part of the light which hasentered from the first surface.
 33. The exposure apparatus according toclaim 30, wherein the light shielding part comprises a metal film. 34.The exposure apparatus according to claim 1, further comprising: firstand second sensors that are arranged to detect the light via theprojection optical system and via the liquid, wherein each of the firstand second sensors comprises a portion of the optical member and thelight-receiving surface.
 35. The exposure apparatus according to claim34, wherein first and second openings are provided on an upper surfaceof the stage, and wherein the first and second sensors are at leastpartly, respectively, disposed at the first and second openings.
 36. Theexposure apparatus according to claim 34, further comprising: a holdingmember arranged to internally hold the optical members of the first andsecond sensors and that is capable of being attached to the stage. 37.The exposure apparatus according to claim 1, wherein the light-receivingsurface is arranged to receive at least the large-angle ray of the lightpassing through the projection optical system under an exposurecondition in which an exposure process is performed.
 38. A devicefabricating method of fabricating a micro-device, comprising:transferring a pattern onto a substrate using the exposure apparatusaccording to claim 1; and processing, based on the pattern, thesubstrate onto which the pattern has been transferred.